Forum | Documentation | Website | Blog

Skip to content
Snippets Groups Projects
  1. Apr 07, 2022
    • Linus Torvalds's avatar
      Merge tag 'random-5.18-rc2-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random · 3638bd90
      Linus Torvalds authored
      Pull random number generator fixes from Jason Donenfeld:
      
       - Another fixup to the fast_init/crng_init split, this time in how much
         entropy is being credited, from Jan Varho.
      
       - As discussed, we now opportunistically call try_to_generate_entropy()
         in /dev/urandom reads, as a replacement for the reverted commit. I
         opted to not do the more invasive wait_for_random_bytes() change at
         least for now, preferring to do something smaller and more obvious
         for the time being, but maybe that can be revisited as things evolve
         later.
      
       - Userspace can use FUSE or userfaultfd or simply move a process to
         idle priority in order to make a read from the random device never
         complete, which breaks forward secrecy, fixed by overwriting
         sensitive bytes early on in the function.
      
       - Jann Horn noticed that /dev/urandom reads were only checking for
         pending signals if need_resched() was true, a bug going back to the
         genesis commit, now fixed by always checking for signal_pending() and
         calling cond_resched(). This explains various noticeable signal
         delivery delays I've seen in programs over the years that do long
         reads from /dev/urandom.
      
       - In order to be more like other devices (e.g. /dev/zero) and to
         mitigate the impact of fixing the above bug, which has been around
         forever (users have never really needed to check the return value of
         read() for medium-sized reads and so perhaps many didn't), we now
         move signal checking to the bottom part of the loop, and do so every
         PAGE_SIZE-bytes.
      
      * tag 'random-5.18-rc2-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
        random: check for signals every PAGE_SIZE chunk of /dev/[u]random
        random: check for signal_pending() outside of need_resched() check
        random: do not allow user to keep crng key around on stack
        random: opportunistically initialize on /dev/urandom reads
        random: do not split fast init input in add_hwgenerator_randomness()
      3638bd90
    • Linus Torvalds's avatar
      Merge tag 'ata-5.18-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/libata · 640b5037
      Linus Torvalds authored
      Pull ata fixes from Damien Le Moal:
      
       - Fix a compilation warning due to an uninitialized variable in
         ata_sff_lost_interrupt(), from me.
      
       - Fix invalid internal command tag handling in the sata_dwc_460ex
         driver, from Christian.
      
       - Disable READ LOG DMA EXT with Samsung 840 EVO SSDs as this command
         causes the drives to hang, from Christian.
      
       - Change the config option CONFIG_SATA_LPM_POLICY back to its original
         name CONFIG_SATA_LPM_MOBILE_POLICY to avoid potential problems with
         users losing their configuration (as discussed during the merge
         window), from Mario.
      
      * tag 'ata-5.18-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/libata:
        ata: ahci: Rename CONFIG_SATA_LPM_POLICY configuration item back
        ata: libata-core: Disable READ LOG DMA EXT for Samsung 840 EVOs
        ata: sata_dwc_460ex: Fix crash due to OOB write
        ata: libata-sff: Fix compilation warning in ata_sff_lost_interrupt()
      640b5037
  2. Apr 06, 2022
    • Jason A. Donenfeld's avatar
      random: check for signals every PAGE_SIZE chunk of /dev/[u]random · e3c1c4fd
      Jason A. Donenfeld authored
      In 1448769c ("random: check for signal_pending() outside of
      need_resched() check"), Jann pointed out that we previously were only
      checking the TIF_NOTIFY_SIGNAL and TIF_SIGPENDING flags if the process
      had TIF_NEED_RESCHED set, which meant in practice, super long reads to
      /dev/[u]random would delay signal handling by a long time. I tried this
      using the below program, and indeed I wasn't able to interrupt a
      /dev/urandom read until after several megabytes had been read. The bug
      he fixed has always been there, and so code that reads from /dev/urandom
      without checking the return value of read() has mostly worked for a long
      time, for most sizes, not just for <= 256.
      
      Maybe it makes sense to keep that code working. The reason it was so
      small prior, ignoring the fact that it didn't work anyway, was likely
      because /dev/random used to block, and that could happen for pretty
      large lengths of time while entropy was gathered. But now, it's just a
      ch...
      e3c1c4fd
    • Jann Horn's avatar
      random: check for signal_pending() outside of need_resched() check · 1448769c
      Jann Horn authored
      signal_pending() checks TIF_NOTIFY_SIGNAL and TIF_SIGPENDING, which
      signal that the task should bail out of the syscall when possible. This
      is a separate concept from need_resched(), which checks
      TIF_NEED_RESCHED, signaling that the task should preempt.
      
      In particular, with the current code, the signal_pending() bailout
      probably won't work reliably.
      
      Change this to look like other functions that read lots of data, such as
      read_zero().
      
      Fixes: 1da177e4
      
       ("Linux-2.6.12-rc2")
      Signed-off-by: default avatarJann Horn <jannh@google.com>
      Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
      1448769c
    • Jason A. Donenfeld's avatar
      random: do not allow user to keep crng key around on stack · aba120cc
      Jason A. Donenfeld authored
      
      The fast key erasure RNG design relies on the key that's used to be used
      and then discarded. We do this, making judicious use of
      memzero_explicit().  However, reads to /dev/urandom and calls to
      getrandom() involve a copy_to_user(), and userspace can use FUSE or
      userfaultfd, or make a massive call, dynamically remap memory addresses
      as it goes, and set the process priority to idle, in order to keep a
      kernel stack alive indefinitely. By probing
      /proc/sys/kernel/random/entropy_avail to learn when the crng key is
      refreshed, a malicious userspace could mount this attack every 5 minutes
      thereafter, breaking the crng's forward secrecy.
      
      In order to fix this, we just overwrite the stack's key with the first
      32 bytes of the "free" fast key erasure output. If we're returning <= 32
      bytes to the user, then we can still return those bytes directly, so
      that short reads don't become slower. And for long reads, the difference
      is hopefully lost in the amortization, so it doesn't change much, with
      that amortization helping variously for medium reads.
      
      We don't need to do this for get_random_bytes() and the various
      kernel-space callers, and later, if we ever switch to always batching,
      this won't be necessary either, so there's no need to change the API of
      these functions.
      
      Cc: Theodore Ts'o <tytso@mit.edu>
      Reviewed-by: default avatarJann Horn <jannh@google.com>
      Fixes: c92e040d ("random: add backtracking protection to the CRNG")
      Fixes: 186873c5
      
       ("random: use simpler fast key erasure flow on per-cpu keys")
      Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
      aba120cc
  3. Apr 05, 2022
  4. Apr 04, 2022
    • Jan Varho's avatar
      random: do not split fast init input in add_hwgenerator_randomness() · 527a9867
      Jan Varho authored
      
      add_hwgenerator_randomness() tries to only use the required amount of input
      for fast init, but credits all the entropy, rather than a fraction of
      it. Since it's hard to determine how much entropy is left over out of a
      non-unformly random sample, either give it all to fast init or credit
      it, but don't attempt to do both. In the process, we can clean up the
      injection code to no longer need to return a value.
      
      Signed-off-by: default avatarJan Varho <jan.varho@gmail.com>
      [Jason: expanded commit message]
      Fixes: 73c7733f ("random: do not throw away excess input to crng_fast_load")
      Cc: stable@vger.kernel.org # 5.17+, requires af704c85
      
      
      Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
      527a9867
  5. Apr 03, 2022
    • Christian Lamparter's avatar
      ata: libata-core: Disable READ LOG DMA EXT for Samsung 840 EVOs · 53997522
      Christian Lamparter authored
      Samsung' 840 EVO with the latest firmware (EXT0DB6Q) locks up with
      the a message: "READ LOG DMA EXT failed, trying PIO" during boot.
      
      Initially this was discovered because it caused a crash
      with the sata_dwc_460ex controller on a WD MyBook Live DUO.
      
      The reporter "Tice Rex" which has the unique opportunity that he
      has two Samsung 840 EVO SSD! One with the older firmware "EXT0BB0Q"
      which booted fine and didn't expose "READ LOG DMA EXT". But the
      newer/latest firmware "EXT0DB6Q" caused the headaches.
      
      BugLink: https://github.com/openwrt/openwrt/issues/9505
      
      
      Signed-off-by: default avatarChristian Lamparter <chunkeey@gmail.com>
      Signed-off-by: default avatarDamien Le Moal <damien.lemoal@opensource.wdc.com>
      53997522
    • Christian Lamparter's avatar
      ata: sata_dwc_460ex: Fix crash due to OOB write · 7aa8104a
      Christian Lamparter authored
      the driver uses libata's "tag" values from in various arrays.
      Since the mentioned patch bumped the ATA_TAG_INTERNAL to 32,
      the value of the SATA_DWC_QCMD_MAX needs to account for that.
      
      Otherwise ATA_TAG_INTERNAL usage cause similar crashes like
      this as reported by Tice Rex on the OpenWrt Forum and
      reproduced (with symbols) here:
      
      | BUG: Kernel NULL pointer dereference at 0x00000000
      | Faulting instruction address: 0xc03ed4b8
      | Oops: Kernel access of bad area, sig: 11 [#1]
      | BE PAGE_SIZE=4K PowerPC 44x Platform
      | CPU: 0 PID: 362 Comm: scsi_eh_1 Not tainted 5.4.163 #0
      | NIP:  c03ed4b8 LR: c03d27e8 CTR: c03ed36c
      | REGS: cfa59950 TRAP: 0300   Not tainted  (5.4.163)
      | MSR:  00021000 <CE,ME>  CR: 42000222  XER: 00000000
      | DEAR: 00000000 ESR: 00000000
      | GPR00: c03d27e8 cfa59a08 cfa55fe0 00000000 0fa46bc0 [...]
      | [..]
      | NIP [c03ed4b8] sata_dwc_qc_issue+0x14c/0x254
      | LR [c03d27e8] ata_qc_issue+0x1c8/0x2dc
      | Call Trace:
      | [cfa59a08] [c003f4e0] __cancel_work_timer+0x12...
      7aa8104a
    • Damien Le Moal's avatar
      ata: libata-sff: Fix compilation warning in ata_sff_lost_interrupt() · 76ed2f61
      Damien Le Moal authored
      When returning false, ata_sff_altstatus() does not return any status
      value, resulting in a compilation warning in ata_sff_lost_interrupt()
      ("uninitialized symbol 'status'"). Fix this by initializing the local
      variable "status" to 0.
      
      Fixes: 03c0e84f
      
       ("ata: libata-sff: refactor ata_sff_altstatus()")
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarDamien Le Moal <damien.lemoal@opensource.wdc.com>
      76ed2f61
    • Linus Torvalds's avatar
      Linux 5.18-rc1 · 31231092
      Linus Torvalds authored
      v5.18-rc1
      31231092
    • Linus Torvalds's avatar
      Merge tag 'trace-v5.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace · 09bb8856
      Linus Torvalds authored
      Pull more tracing updates from Steven Rostedt:
      
       - Rename the staging files to give them some meaning. Just
         stage1,stag2,etc, does not show what they are for
      
       - Check for NULL from allocation in bootconfig
      
       - Hold event mutex for dyn_event call in user events
      
       - Mark user events to broken (to work on the API)
      
       - Remove eBPF updates from user events
      
       - Remove user events from uapi header to keep it from being installed.
      
       - Move ftrace_graph_is_dead() into inline as it is called from hot
         paths and also convert it into a static branch.
      
      * tag 'trace-v5.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
        tracing: Move user_events.h temporarily out of include/uapi
        ftrace: Make ftrace_graph_is_dead() a static branch
        tracing: Set user_events to BROKEN
        tracing/user_events: Remove eBPF interfaces
        tracing/user_events: Hold event_mutex during dyn_event_add
        proc: bootconfig: A...
      09bb8856
    • Linus Torvalds's avatar
      Merge tag 'clk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux · 34a53ff9
      Linus Torvalds authored
      Pull clk fix from Stephen Boyd:
       "A single revert to fix a boot regression seen when clk_put() started
        dropping rate range requests. It's best to keep various systems
        booting so we'll kick this out and try again next time"
      
      * tag 'clk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
        Revert "clk: Drop the rate range on clk_put()"
      34a53ff9
    • Linus Torvalds's avatar
      Merge tag 'x86-urgent-2022-04-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 8b5656bc
      Linus Torvalds authored
      Pull x86 fixes from Thomas Gleixner:
       "A set of x86 fixes and updates:
      
         - Make the prctl() for enabling dynamic XSTATE components correct so
           it adds the newly requested feature to the permission bitmap
           instead of overwriting it. Add a selftest which validates that.
      
         - Unroll string MMIO for encrypted SEV guests as the hypervisor
           cannot emulate it.
      
         - Handle supervisor states correctly in the FPU/XSTATE code so it
           takes the feature set of the fpstate buffer into account. The
           feature sets can differ between host and guest buffers. Guest
           buffers do not contain supervisor states. So far this was not an
           issue, but with enabling PASID it needs to be handled in the buffer
           offset calculation and in the permission bitmaps.
      
         - Avoid a gazillion of repeated CPUID invocations in by caching the
           values early in the FPU/XSTATE code.
      
         - Enable CONFIG_WERROR in x86 defconfig.
      
         - Make the X86 defconfigs more useful by adapting them to Y2022
           reality"
      
      * tag 'x86-urgent-2022-04-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        x86/fpu/xstate: Consolidate size calculations
        x86/fpu/xstate: Handle supervisor states in XSTATE permissions
        x86/fpu/xsave: Handle compacted offsets correctly with supervisor states
        x86/fpu: Cache xfeature flags from CPUID
        x86/fpu/xsave: Initialize offset/size cache early
        x86/fpu: Remove unused supervisor only offsets
        x86/fpu: Remove redundant XCOMP_BV initialization
        x86/sev: Unroll string mmio with CC_ATTR_GUEST_UNROLL_STRING_IO
        x86/config: Make the x86 defconfigs a bit more usable
        x86/defconfig: Enable WERROR
        selftests/x86/amx: Update the ARCH_REQ_XCOMP_PERM test
        x86/fpu/xstate: Fix the ARCH_REQ_XCOMP_PERM implementation
      8b5656bc
    • Linus Torvalds's avatar
      Merge tag 'core-urgent-2022-04-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · e235f419
      Linus Torvalds authored
      Pull RT signal fix from Thomas Gleixner:
       "Revert the RT related signal changes. They need to be reworked and
        generalized"
      
      * tag 'core-urgent-2022-04-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels"
      e235f419
    • Linus Torvalds's avatar
      Merge tag 'dma-mapping-5.18-1' of git://git.infradead.org/users/hch/dma-mapping · 63d12cc3
      Linus Torvalds authored
      Pull more dma-mapping updates from Christoph Hellwig:
      
       - fix a regression in dma remap handling vs AMD memory encryption (me)
      
       - finally kill off the legacy PCI DMA API (Christophe JAILLET)
      
      * tag 'dma-mapping-5.18-1' of git://git.infradead.org/users/hch/dma-mapping:
        dma-mapping: move pgprot_decrypted out of dma_pgprot
        PCI/doc: cleanup references to the legacy PCI DMA API
        PCI: Remove the deprecated "pci-dma-compat.h" API
      63d12cc3
    • Linus Torvalds's avatar
      Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm · 5dee8721
      Linus Torvalds authored
      Pull ARM fixes from Russell King:
      
       - avoid unnecessary rebuilds for library objects
      
       - fix return value of __setup handlers
      
       - fix invalid input check for "crashkernel=" kernel option
      
       - silence KASAN warnings in unwind_frame
      
      * tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
        ARM: 9191/1: arm/stacktrace, kasan: Silence KASAN warnings in unwind_frame()
        ARM: 9190/1: kdump: add invalid input check for 'crashkernel=0'
        ARM: 9187/1: JIVE: fix return value of __setup handler
        ARM: 9189/1: decompressor: fix unneeded rebuilds of library objects
      5dee8721
  6. Apr 02, 2022