In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to do sanity check on destination blkaddr during recovery
As Wenqing Liu reported in bugzilla:
https://bugzilla.kernel.org/show_bug.cgi?id=216456
loop5: detected capacity change from 0 to 131072 F2FS-fs (loop5): recover_inode: ino = 6, name = hln, inline = 1 F2FS-fs (loop5): recover_data: ino = 6 (i_size: recover) err = 0 F2FS-fs (loop5): recover_inode: ino = 6, name = hln, inline = 1 F2FS-fs (loop5): recover_data: ino = 6 (i_size: recover) err = 0 F2FS-fs (loop5): recover_inode: ino = 6, name = hln, inline = 1 F2FS-fs (loop5): recover_data: ino = 6 (i_size: recover) err = 0 F2FS-fs (loop5): Bitmap was wrongly set, blk:5634 ------------[ cut here ]------------ WARNING: CPU: 3 PID: 1013 at fs/f2fs/segment.c:2198 RIP: 0010:update_sit_entry+0xa55/0x10b0 [f2fs] Call Trace: <TASK> f2fs_do_replace_block+0xa98/0x1890 [f2fs] f2fs_replace_block+0xeb/0x180 [f2fs] recover_data+0x1a69/0x6ae0 [f2fs] f2fs_recover_fsync_data+0x120d/0x1fc0 [f2fs] f2fs_fill_super+0x4665/0x61e0 [f2fs] mount_bdev+0x2cf/0x3b0 legacy_get_tree+0xed/0x1d0 vfs_get_tree+0x81/0x2b0 path_mount+0x47e/0x19d0 do_mount+0xce/0xf0 __x64_sys_mount+0x12c/0x1a0 do_syscall_64+0x38/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd
If we enable CONFIG_F2FS_CHECK_FS config, it will trigger a kernel panic instead of warning.
The root cause is: in fuzzed image, SIT table is inconsistent with inode mapping table, result in triggering such warning during SIT table update.
This patch introduces a new flag DATA_GENERIC_ENHANCE_UPDATE, w/ this flag, data block recovery flow can check destination blkaddr's validation in SIT table, and skip f2fs_replace_block() to avoid inconsistent status.
Exploitability
AV:LAC:LPR:LUI:NScope
S:UImpact
C:NI:NA:H5.5/CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H