From: Qu Wenruo <wqu@suse.com>
To: fdmanana@kernel.org, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] btrfs: fix invalid inode pointer after failure to create reloc inode
Date: Sun, 6 Apr 2025 07:11:10 +0930 [thread overview]
Message-ID: <45e9ea01-42ce-4c31-b7ba-833d54145a2e@suse.com> (raw)
In-Reply-To: <9ac220a55a540ad22f7cb198856b689079f3e8c6.1743875430.git.fdmanana@suse.com>
在 2025/4/6 03:21, fdmanana@kernel.org 写道:
> From: Filipe Manana <fdmanana@suse.com>
>
> If we have a failure at create_reloc_inode(), under the 'out' label we
> assign an error pointer to the 'inode' variable and then return a weird
> pointer because we return the expression "&inode->vfs_inode":
>
> static noinline_for_stack struct inode *create_reloc_inode(
> const struct btrfs_block_group *group)
> {
> (...)
> out:
> (...)
> if (ret) {
> if (inode)
> iput(&inode->vfs_inode);
> inode = ERR_PTR(ret);
> }
> return &inode->vfs_inode;
> }
>
> This can make us return a pointer that is not an error pointer and make
> the caller proceed as if an error didn't happen and later result in an
> invalid memory access when dereferencing the inode pointer. The syzbot
> reported such a case with the following stack trace:
>
> R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
> R13: 0000000000000000 R14: 431bde82d7b634db R15: 00007ffc55de5790
> </TASK>
> BTRFS info (device loop0): relocating block group 6881280 flags data|metadata
> Oops: general protection fault, probably for non-canonical address 0xdffffc0000000045: 0000 [#1] SMP KASAN NOPTI
> KASAN: null-ptr-deref in range [0x0000000000000228-0x000000000000022f]
> CPU: 0 UID: 0 PID: 5332 Comm: syz-executor215 Not tainted 6.14.0-syzkaller-13423-ga8662bcd2ff1 #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> RIP: 0010:relocate_file_extent_cluster+0xe7/0x1750 fs/btrfs/relocation.c:2971
> Code: 00 74 08 48 89 df e8 f8 36 24 fe 48 89 9c 24 30 01 00 00 4c 89 74 24 28 4d 8b 76 10 49 8d 9e 98 fe ff ff 48 89 d8 48 c1 e8 03 <42> 80 3c 20 00 74 08 48 89 df e8 ca 36 24 fe 4c 8b 3b 48 8b 44 24
> RSP: 0018:ffffc9000d3375e0 EFLAGS: 00010203
> RAX: 0000000000000045 RBX: 000000000000022c RCX: ffff888000562440
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880452db000
> RBP: ffffc9000d337870 R08: ffffffff84089251 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
> R13: ffffffff9368a020 R14: 0000000000000394 R15: ffff8880452db000
> FS: 000055558bc7b380(0000) GS:ffff88808c596000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000055a7a192e740 CR3: 0000000036e2e000 CR4: 0000000000352ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> relocate_block_group+0xa1e/0xd50 fs/btrfs/relocation.c:3657
> btrfs_relocate_block_group+0x777/0xd80 fs/btrfs/relocation.c:4011
> btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3511
> __btrfs_balance+0x1a93/0x25e0 fs/btrfs/volumes.c:4292
> btrfs_balance+0xbde/0x10c0 fs/btrfs/volumes.c:4669
> btrfs_ioctl_balance+0x3f5/0x660 fs/btrfs/ioctl.c:3586
> vfs_ioctl fs/ioctl.c:51 [inline]
> __do_sys_ioctl fs/ioctl.c:906 [inline]
> __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:892
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fb4ef537dd9
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 01 1b 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 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:00007ffc55de5728 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00007ffc55de5750 RCX: 00007fb4ef537dd9
> RDX: 0000200000000440 RSI: 00000000c4009420 RDI: 0000000000000003
> RBP: 0000000000000002 R08: 00007ffc55de54c6 R09: 00007ffc55de5770
> R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
> R13: 0000000000000000 R14: 431bde82d7b634db R15: 00007ffc55de5790
> </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:relocate_file_extent_cluster+0xe7/0x1750 fs/btrfs/relocation.c:2971
> Code: 00 74 08 48 89 df e8 f8 36 24 fe 48 89 9c 24 30 01 00 00 4c 89 74 24 28 4d 8b 76 10 49 8d 9e 98 fe ff ff 48 89 d8 48 c1 e8 03 <42> 80 3c 20 00 74 08 48 89 df e8 ca 36 24 fe 4c 8b 3b 48 8b 44 24
> RSP: 0018:ffffc9000d3375e0 EFLAGS: 00010203
> RAX: 0000000000000045 RBX: 000000000000022c RCX: ffff888000562440
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880452db000
> RBP: ffffc9000d337870 R08: ffffffff84089251 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
> R13: ffffffff9368a020 R14: 0000000000000394 R15: ffff8880452db000
> FS: 000055558bc7b380(0000) GS:ffff88808c596000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000055a7a192e740 CR3: 0000000036e2e000 CR4: 0000000000352ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> ----------------
> Code disassembly (best guess):
> 0: 00 74 08 48 add %dh,0x48(%rax,%rcx,1)
> 4: 89 df mov %ebx,%edi
> 6: e8 f8 36 24 fe call 0xfe243703
> b: 48 89 9c 24 30 01 00 mov %rbx,0x130(%rsp)
> 12: 00
> 13: 4c 89 74 24 28 mov %r14,0x28(%rsp)
> 18: 4d 8b 76 10 mov 0x10(%r14),%r14
> 1c: 49 8d 9e 98 fe ff ff lea -0x168(%r14),%rbx
> 23: 48 89 d8 mov %rbx,%rax
> 26: 48 c1 e8 03 shr $0x3,%rax
> * 2a: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction
> 2f: 74 08 je 0x39
> 31: 48 89 df mov %rbx,%rdi
> 34: e8 ca 36 24 fe call 0xfe243703
> 39: 4c 8b 3b mov (%rbx),%r15
> 3c: 48 rex.W
> 3d: 8b .byte 0x8b
> 3e: 44 rex.R
> 3f: 24 .byte 0x24
>
> So fix this by returning the error immediately.
>
> Fixes: 00aad5080c51 ("btrfs: make btrfs_iget() return a btrfs inode instead")
> Reported-by: syzbot+7481815bb47ef3e702e2@syzkaller.appspotmail.com
> Link: https://lore.kernel.org/linux-btrfs/67f14ee9.050a0220.0a13.023e.GAE@google.com/
> Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Thanks,
Qu
> ---
> fs/btrfs/relocation.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 62b69274ec03..4bfc5403cf17 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -3801,7 +3801,7 @@ static noinline_for_stack struct inode *create_reloc_inode(
> if (ret) {
> if (inode)
> iput(&inode->vfs_inode);
> - inode = ERR_PTR(ret);
> + return ERR_PTR(ret);
> }
> return &inode->vfs_inode;
> }
next prev parent reply other threads:[~2025-04-05 21:41 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-05 17:51 [PATCH] btrfs: fix invalid inode pointer after failure to create reloc inode fdmanana
2025-04-05 21:41 ` Qu Wenruo [this message]
2025-04-07 5:55 ` Johannes Thumshirn
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