Re: [PATCH] jfs: fix array-index-out-of-bounds in diNewExt

Dave Kleikamp
2023-12-20T20:02:58Z

On 12/11/23 7:36PM, Edward Adam Davis wrote:
> [Syz report]
> UBSAN: array-index-out-of-bounds in fs/jfs/jfs_imap.c:2360:2
> index -878706688 is out of range for type 'struct iagctl[128]'
> CPU: 1 PID: 5065 Comm: syz-executor282 Not tainted 6.7.0-rc4-syzkaller-00009-gbee0e7762ad2 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:88 [inline]
> dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
> ubsan_epilogue lib/ubsan.c:217 [inline]
> __ubsan_handle_out_of_bounds+0x11c/0x150 lib/ubsan.c:348
> diNewExt+0x3cf3/0x4000 fs/jfs/jfs_imap.c:2360
> diAllocExt fs/jfs/jfs_imap.c:1949 [inline]
> diAllocAG+0xbe8/0x1e50 fs/jfs/jfs_imap.c:1666
> diAlloc+0x1d3/0x1760 fs/jfs/jfs_imap.c:1587
> ialloc+0x8f/0x900 fs/jfs/jfs_inode.c:56
> jfs_mkdir+0x1c5/0xb90 fs/jfs/namei.c:225
> vfs_mkdir+0x2f1/0x4b0 fs/namei.c:4106
> do_mkdirat+0x264/0x3a0 fs/namei.c:4129
> __do_sys_mkdir fs/namei.c:4149 [inline]
> __se_sys_mkdir fs/namei.c:4147 [inline]
> __x64_sys_mkdir+0x6e/0x80 fs/namei.c:4147
> do_syscall_x64 arch/x86/entry/common.c:51 [inline]
> do_syscall_64+0x45/0x110 arch/x86/entry/common.c:82
> entry_SYSCALL_64_after_hwframe+0x63/0x6b
> RIP: 0033:0x7fcb7e6a0b57
> Code: ff ff 77 07 31 c0 c3 0f 1f 40 00 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 b8 53 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffd83023038 EFLAGS: 00000286 ORIG_RAX: 0000000000000053
> RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007fcb7e6a0b57
> RDX: 00000000000a1020 RSI: 00000000000001ff RDI: 0000000020000140
> RBP: 0000000020000140 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000286 R12: 00007ffd830230d0
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>
> [Analysis]
> When the agstart is too large, it can cause agno overflow.
>
> [Fix]
> After obtaining agno, if the value is invalid, exit the subsequent process.

Looks good. Applied.

Shaggy

>
> Reported-and-tested-by: syzbot+553d90297e6d2f50dbc7@syzkaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
> fs/jfs/jfs_imap.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
> index a037ee59e398..cc5819b3ec9a 100644
> --- a/fs/jfs/jfs_imap.c
> +++ b/fs/jfs/jfs_imap.c
> @@ -2179,6 +2179,9 @@ static int diNewExt(struct inomap * imap, struct iag * iagp, int extno)
> /* get the ag and iag numbers for this iag.
> */
> agno = BLKTOAG(le64_to_cpu(iagp->agstart), sbi);
> + if (agno > MAXAG || agno < 0)
> + return -EIO;
> +
> iagno = le32_to_cpu(iagp->iagnum);
>
> /* check if this is the last free extent within the