CVE-2022-49352

In the Linux kernel, the following vulnerability has been resolved:

ext4: fix warning in ext4_handle_inode_extension

We got issue as follows: EXT4-fs error (device loop0) in ext4_reserve_inode_write:5741: Out of memory EXT4-fs error (device loop0): ext4_setattr:5462: inode #13: comm syz-executor.0: mark_inode_dirty error EXT4-fs error (device loop0) in ext4_setattr:5519: Out of memory EXT4-fs error (device loop0): ext4_ind_map_blocks:595: inode #13: comm syz-executor.0: Cant allocate blocks for non-extent mapped inodes with bigalloc ————[ cut here ]———— WARNING: CPU: 1 PID: 4361 at fs/ext4/file.c:301 ext4_file_write_iter+0x11c9/0x1220 Modules linked in: CPU: 1 PID: 4361 Comm: syz-executor.0 Not tainted 5.10.0+ #1 RIP: 0010:ext4_file_write_iter+0x11c9/0x1220 RSP: 0018:ffff924d80b27c00 EFLAGS: 00010282 RAX: ffffffff815a3379 RBX: 0000000000000000 RCX: 000000003b000000 RDX: ffff924d81601000 RSI: 00000000000009cc RDI: 00000000000009cd RBP: 000000000000000d R08: ffffffffbc5a2c6b R09: 0000902e0e52a96f R10: ffff902e2b7c1b40 R11: ffff902e2b7c1b40 R12: 000000000000000a R13: 0000000000000001 R14: ffff902e0e52aa10 R15: ffffffffffffff8b FS: 00007f81a7f65700(0000) GS:ffff902e3bc80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 000000012db88001 CR4: 00000000003706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: do_iter_readv_writev+0x2e5/0x360 do_iter_write+0x112/0x4c0 do_pwritev+0x1e5/0x390 __x64_sys_pwritev2+0x7e/0xa0 do_syscall_64+0x37/0x50 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Above issue may happen as follows: Assume inode.i_size=4096 EXT4_I(inode)->i_disksize=4096

step 1: set inode->i_isize = 8192 ext4_setattr if (attr->ia_size != inode->i_size) EXT4_I(inode)->i_disksize = attr->ia_size; rc = ext4_mark_inode_dirty ext4_reserve_inode_write ext4_get_inode_loc __ext4_get_inode_loc sb_getblk –> return -ENOMEM … if (!error) ->will not update i_size i_size_write(inode, attr->ia_size); Now: inode.i_size=4096 EXT4_I(inode)->i_disksize=8192

step 2: Direct write 4096 bytes ext4_file_write_iter ext4_dio_write_iter iomap_dio_rw ->return error if (extend) ext4_handle_inode_extension WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize); ->Then trigger warning.

To solve above issue, if mark inode dirty failed in ext4_setattr just set EXT4_I(inode)->i_disksize with old value.

Affected Software

References

• https://git.kernel.org/stable/c/0ab308d72af7548f21e4499d025c25887da0c26a
• https://git.kernel.org/stable/c/1bcce88da60eccc946c0f4ed942b0f08cd565778
• https://git.kernel.org/stable/c/adf490083ca52ebfb0b2fe64ff1ead00c0452dd7
• https://git.kernel.org/stable/c/b81d2ff6885e38fc745eeaf9565775055778fc0b
• https://git.kernel.org/stable/c/e383c2aa5f02ab571530dc5c5696479672478c25
• https://git.kernel.org/stable/c/f4534c9fc94d22383f187b9409abb3f9df2e3db3