The patch titled
Subject: mm: mmap: Fix general protection fault in unlink_file_vma()
has been added to the -mm tree. Its filename is
mm-mmap-fix-general-protection-fault-in-unlink_file_vma.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-mmap-fix-general-protection-fault-in-unlink_file_vma.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-mmap-fix-general-protection-fault-in-unlink_file_vma.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm: mmap: Fix general protection fault in unlink_file_vma()
The syzbot reported the below general protection fault:
general protection fault, probably for non-canonical address
0xe00eeaee0000003b: 0000 [#1] PREEMPT SMP KASAN
KASAN: maybe wild-memory-access in range
[0x00777770000001d8-0x00777770000001df]
CPU: 1 PID: 10488 Comm: syz-executor721 Not tainted 5.9.0-rc3-syzkaller #0
RIP: 0010:unlink_file_vma+0x57/0xb0 mm/mmap.c:164
Code: 4c 8b a5 a0 00 00 00 4d 85 e4 74 4e e8 92 d7 cd ff 49 8d bc 24
d8 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c
02 00 75 3d 4d 8b b4 24 d8 01 00 00 4d 8d 6e 78 4c 89 ef e8
RSP: 0018:ffffc9000ac0f9b0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff88800010ceb0 RCX: ffffffff81592421
RDX: 000eeeee0000003b RSI: ffffffff81a6736e RDI: 00777770000001d8
RBP: ffff88800010ceb0 R08: 0000000000000001 R09: ffff88801291a50f
R10: ffffed10025234a1 R11: 0000000000000001 R12: 0077777000000000
R13: 00007f1eea0da000 R14: 00007f1eea0d9000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880ae700000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1eea11a9d0 CR3: 000000000007e000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
free_pgtables+0x1b3/0x2f0 mm/memory.c:415
exit_mmap+0x2c0/0x530 mm/mmap.c:3184
__mmput+0x122/0x470 kernel/fork.c:1076
mmput+0x53/0x60 kernel/fork.c:1097
exit_mm kernel/exit.c:483 [inline]
do_exit+0xa8b/0x29f0 kernel/exit.c:793
do_group_exit+0x125/0x310 kernel/exit.c:903
get_signal+0x428/0x1f00 kernel/signal.c:2757
arch_do_signal+0x82/0x2520 arch/x86/kernel/signal.c:811
exit_to_user_mode_loop kernel/entry/common.c:136 [inline]
exit_to_user_mode_prepare+0x1ae/0x200 kernel/entry/common.c:167
syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:242
entry_SYSCALL_64_after_hwframe+0x44/0xa9
It's because the ->mmap() callback can change vma->vm_file and fput the
original file. But the commit d70cec898324 ("mm: mmap: merge vma after
call_mmap() if possible") failed to catch this case and always fput() the
original file, hence add an extra fput().
[ Thanks Hillf for pointing this extra fput() out. ]
Link: https://lkml.kernel.org/r/20200916090733.31427-1-linmiaohe@xxxxxxxxxx
Fixes: d70cec898324 ("mm: mmap: merge vma after call_mmap() if possible")
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Reported-by: syzbot+c5d5a51dcbb558ca0cb5@xxxxxxxxxxxxxxxxxxxxxxxxx
Cc: Hongxiang Lou <louhongxiang@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/mm/mmap.c~mm-mmap-fix-general-protection-fault-in-unlink_file_vma
+++ a/mm/mmap.c
@@ -1781,7 +1781,11 @@ unsigned long mmap_region(struct file *f
merge = vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags,
NULL, vma->vm_file, vma->vm_pgoff, NULL, NULL_VM_UFFD_CTX);
if (merge) {
- fput(file);
+ /* ->mmap() can change vma->vm_file and fput the original file. So
+ * fput the vma->vm_file here or we would add an extra fput for file
+ * and cause general protection fault ultimately.
+ */
+ fput(vma->vm_file);
vm_area_free(vma);
vma = merge;
/* Update vm_flags and possible addr to pick up the change. We don't
_
Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are
mm-mmap-fix-general-protection-fault-in-unlink_file_vma.patch
mm-swap-fix-confusing-comment-in-release_pages.patch
mm-swap_slotsc-remove-always-zero-and-unused-return-value-of-enable_swap_slots_cache.patch
mm-remove-useless-out-label-in-__swap_writepage.patch
mm-fix-incomplete-comment-in-lru_cache_add_inactive_or_unevictable.patch
mm-remove-unnecessary-goto-out-in-_swap_info_get.patch
mm-fix-potential-memory-leak-in-sys_swapon.patch
mm-memcontrol-correct-the-comment-of-mem_cgroup_iter.patch
mm-page_counter-correct-the-obsolete-func-name-in-the-comment-of-page_counter_try_charge.patch
mm-memcontrol-reword-obsolete-comment-of-mem_cgroup_unmark_under_oom.patch
mm-use-helper-function-mapping_allow_writable.patch
mm-mmap-use-helper-function-allow_write_access-in-__remove_shared_vm_struct.patch
mm-mempool-add-else-to-split-mutually-exclusive-case.patch
mm-vmstat-use-helper-macro-abs.patch
mm-fix-some-broken-comments.patch
mm-use-helper-function-put_write_access.patch
percpu_counter-use-helper-macro-abs.patch
mm-migrate-avoid-possible-unnecessary-process-right-check-in-kernel_move_pages.patch
