On Thu, 22 Sep 2022 20:04:34 +0800, Baokun Li wrote:
If the starting position of our insert range happens to be in the holeApplied, thanks!
between the two ext4_extent_idx, because the lblk of the ext4_extent in
the previous ext4_extent_idx is always less than the start, which leads
to the "extent" variable access across the boundary, the following UAF is
triggered:
==================================================================
BUG: KASAN: use-after-free in ext4_ext_shift_extents+0x257/0x790
Read of size 4 at addr ffff88819807a008 by task fallocate/8010
CPU: 3 PID: 8010 Comm: fallocate Tainted: G E 5.10.0+ #492
Call Trace:
dump_stack+0x7d/0xa3
print_address_description.constprop.0+0x1e/0x220
kasan_report.cold+0x67/0x7f
ext4_ext_shift_extents+0x257/0x790
ext4_insert_range+0x5b6/0x700
ext4_fallocate+0x39e/0x3d0
vfs_fallocate+0x26f/0x470
ksys_fallocate+0x3a/0x70
__x64_sys_fallocate+0x4f/0x60
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
==================================================================
[...]
[1/1] ext4: fix use-after-free in ext4_ext_shift_extents
(no commit info)
Best regards,