| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-42251: mm: page_ref: remove folio_try_get_rcu() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| mm: page_ref: remove folio_try_get_rcu() |
| |
| The below bug was reported on a non-SMP kernel: |
| |
| [ 275.267158][ T4335] ------------[ cut here ]------------ |
| [ 275.267949][ T4335] kernel BUG at include/linux/page_ref.h:275! |
| [ 275.268526][ T4335] invalid opcode: 0000 [#1] KASAN PTI |
| [ 275.269001][ T4335] CPU: 0 PID: 4335 Comm: trinity-c3 Not tainted 6.7.0-rc4-00061-gefa7df3e3bb5 #1 |
| [ 275.269787][ T4335] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 |
| [ 275.270679][ T4335] RIP: 0010:try_get_folio (include/linux/page_ref.h:275 (discriminator 3) mm/gup.c:79 (discriminator 3)) |
| [ 275.272813][ T4335] RSP: 0018:ffffc90005dcf650 EFLAGS: 00010202 |
| [ 275.273346][ T4335] RAX: 0000000000000246 RBX: ffffea00066e0000 RCX: 0000000000000000 |
| [ 275.274032][ T4335] RDX: fffff94000cdc007 RSI: 0000000000000004 RDI: ffffea00066e0034 |
| [ 275.274719][ T4335] RBP: ffffea00066e0000 R08: 0000000000000000 R09: fffff94000cdc006 |
| [ 275.275404][ T4335] R10: ffffea00066e0037 R11: 0000000000000000 R12: 0000000000000136 |
| [ 275.276106][ T4335] R13: ffffea00066e0034 R14: dffffc0000000000 R15: ffffea00066e0008 |
| [ 275.276790][ T4335] FS: 00007fa2f9b61740(0000) GS:ffffffff89d0d000(0000) knlGS:0000000000000000 |
| [ 275.277570][ T4335] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| [ 275.278143][ T4335] CR2: 00007fa2f6c00000 CR3: 0000000134b04000 CR4: 00000000000406f0 |
| [ 275.278833][ T4335] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 |
| [ 275.279521][ T4335] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 |
| [ 275.280201][ T4335] Call Trace: |
| [ 275.280499][ T4335] <TASK> |
| [ 275.280751][ T4335] ? die (arch/x86/kernel/dumpstack.c:421 arch/x86/kernel/dumpstack.c:434 arch/x86/kernel/dumpstack.c:447) |
| [ 275.281087][ T4335] ? do_trap (arch/x86/kernel/traps.c:112 arch/x86/kernel/traps.c:153) |
| [ 275.281463][ T4335] ? try_get_folio (include/linux/page_ref.h:275 (discriminator 3) mm/gup.c:79 (discriminator 3)) |
| [ 275.281884][ T4335] ? try_get_folio (include/linux/page_ref.h:275 (discriminator 3) mm/gup.c:79 (discriminator 3)) |
| [ 275.282300][ T4335] ? do_error_trap (arch/x86/kernel/traps.c:174) |
| [ 275.282711][ T4335] ? try_get_folio (include/linux/page_ref.h:275 (discriminator 3) mm/gup.c:79 (discriminator 3)) |
| [ 275.283129][ T4335] ? handle_invalid_op (arch/x86/kernel/traps.c:212) |
| [ 275.283561][ T4335] ? try_get_folio (include/linux/page_ref.h:275 (discriminator 3) mm/gup.c:79 (discriminator 3)) |
| [ 275.283990][ T4335] ? exc_invalid_op (arch/x86/kernel/traps.c:264) |
| [ 275.284415][ T4335] ? asm_exc_invalid_op (arch/x86/include/asm/idtentry.h:568) |
| [ 275.284859][ T4335] ? try_get_folio (include/linux/page_ref.h:275 (discriminator 3) mm/gup.c:79 (discriminator 3)) |
| [ 275.285278][ T4335] try_grab_folio (mm/gup.c:148) |
| [ 275.285684][ T4335] __get_user_pages (mm/gup.c:1297 (discriminator 1)) |
| [ 275.286111][ T4335] ? __pfx___get_user_pages (mm/gup.c:1188) |
| [ 275.286579][ T4335] ? __pfx_validate_chain (kernel/locking/lockdep.c:3825) |
| [ 275.287034][ T4335] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 1)) |
| [ 275.287416][ T4335] __gup_longterm_locked (mm/gup.c:1509 mm/gup.c:2209) |
| [ 275.288192][ T4335] ? __pfx___gup_longterm_locked (mm/gup.c:2204) |
| [ 275.288697][ T4335] ? __pfx_lock_acquire (kernel/locking/lockdep.c:5722) |
| [ 275.289135][ T4335] ? __pfx___might_resched (kernel/sched/core.c:10106) |
| [ 275.289595][ T4335] pin_user_pages_remote (mm/gup.c:3350) |
| [ 275.290041][ T4335] ? __pfx_pin_user_pages_remote (mm/gup.c:3350) |
| [ 275.290545][ T4335] ? find_held_lock (kernel/locking/lockdep.c:5244 (discriminator 1)) |
| [ 275.290961][ T4335] ? mm_access (kernel/fork.c:1573) |
| [ 275.291353][ T4335] process_vm_rw_single_vec+0x142/0x360 |
| [ 275.291900][ T4335] ? __pfx_process_vm_rw_single_vec+0x10/0x10 |
| [ 275.292471][ T4335] ? mm_access (kernel/fork.c:1573) |
| [ 275.292859][ T4335] process_vm_rw_core+0x272/0x4e0 |
| [ 275.293384][ T4335] ? hlock_class (arch/x86/include/asm/bitops.h:227 arch/x86/include/asm/bitops.h:239 include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:228) |
| [ 275.293780][ T4335] ? __pfx_process_vm_rw_core+0x10/0x10 |
| [ 275.294350][ T4335] process_vm_rw (mm/process_vm_access.c:284) |
| [ 275.294748][ T4335] ? __pfx_process_vm_rw (mm/process_vm_access.c:259) |
| [ 275.295197][ T4335] ? __task_pid_nr_ns (include/linux/rcupdate.h:306 (discriminator 1) include/linux/rcupdate.h:780 (discriminator 1) kernel/pid.c:504 (discriminator 1)) |
| [ 275.295634][ T4335] __x64_sys_process_vm_readv (mm/process_vm_access.c:291) |
| [ 275.296139][ T4335] ? syscall_enter_from_user_mode (kernel/entry/common.c:94 kernel/entry/common.c:112) |
| [ 275.296642][ T4335] do_syscall_64 (arch/x86/entry/common.c:51 (discriminator 1) arch/x86/entry/common.c:82 (discriminator 1)) |
| [ 275.297032][ T4335] ? __task_pid_nr_ns (include/linux/rcupdate.h:306 (discriminator 1) include/linux/rcupdate.h:780 (discriminator 1) kernel/pid.c:504 (discriminator 1)) |
| [ 275.297470][ T4335] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4300 kernel/locking/lockdep.c:4359) |
| [ 275.297988][ T4335] ? do_syscall_64 (arch/x86/include/asm/cpufeature.h:171 arch/x86/entry/common.c:97) |
| [ 275.298389][ T4335] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4300 kernel/locking/lockdep.c:4359) |
| [ 275.298906][ T4335] ? do_syscall_64 (arch/x86/include/asm/cpufeature.h:171 arch/x86/entry/common.c:97) |
| [ 275.299304][ T4335] ? do_syscall_64 (arch/x86/include/asm/cpufeature.h:171 arch/x86/entry/common.c:97) |
| [ 275.299703][ T4335] ? do_syscall_64 (arch/x86/include/asm/cpufeature.h:171 arch/x86/entry/common.c:97) |
| [ 275.300115][ T4335] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:129) |
| |
| This BUG is the VM_BUG_ON(!in_atomic() && !irqs_disabled()) assertion in |
| folio_ref_try_add_rcu() for non-SMP kernel. |
| |
| The process_vm_readv() calls GUP to pin the THP. An optimization for |
| pinning THP instroduced by commit 57edfcfd3419 ("mm/gup: accelerate thp |
| gup even for "pages != NULL"") calls try_grab_folio() to pin the THP, |
| but try_grab_folio() is supposed to be called in atomic context for |
| non-SMP kernel, for example, irq disabled or preemption disabled, due to |
| the optimization introduced by commit e286781d5f2e ("mm: speculative |
| page references"). |
| |
| The commit efa7df3e3bb5 ("mm: align larger anonymous mappings on THP |
| boundaries") is not actually the root cause although it was bisected to. |
| It just makes the problem exposed more likely. |
| |
| The follow up discussion suggested the optimization for non-SMP kernel |
| may be out-dated and not worth it anymore [1]. So removing the |
| optimization to silence the BUG. |
| |
| However calling try_grab_folio() in GUP slow path actually is |
| unnecessary, so the following patch will clean this up. |
| |
| [1] https://lore.kernel.org/linux-mm/821cf1d6-92b9-4ac4-bacc-d8f2364ac14f@paulmck-laptop/ |
| |
| The Linux kernel CVE team has assigned CVE-2024-42251 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.6 with commit 57edfcfd3419b4799353d8cbd6ce49da075cfdbd and fixed in 6.6.42 with commit 16380f52b72166d6a33b508cc2509716f436253f |
| Issue introduced in 6.6 with commit 57edfcfd3419b4799353d8cbd6ce49da075cfdbd and fixed in 6.9.11 with commit e7db2762ea3e69f215b3ec4db666006deccc37b4 |
| Issue introduced in 6.6 with commit 57edfcfd3419b4799353d8cbd6ce49da075cfdbd and fixed in 6.10 with commit fa2690af573dfefb47ba6eef888797a64b6b5f3c |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2024-42251 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| include/linux/page_ref.h |
| mm/filemap.c |
| mm/gup.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/16380f52b72166d6a33b508cc2509716f436253f |
| https://git.kernel.org/stable/c/e7db2762ea3e69f215b3ec4db666006deccc37b4 |
| https://git.kernel.org/stable/c/fa2690af573dfefb47ba6eef888797a64b6b5f3c |
