Re: [syzbot] [overlayfs?] memory leak in ovl_parse_param

[Amir Goldstein]

On Sun, Nov 12, 2023 at 6:18 AM syzbot
<syzbot+26eedf3631650972f17c@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    13d88ac54ddd Merge tag 'vfs-6.7.fsid' of git://git.kernel...
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=121cf047680000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=ecfdf78a410c834
> dashboard link: https://syzkaller.appspot.com/bug?extid=26eedf3631650972f17c
> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15c7a6eb680000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13f8b787680000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/9bb27a01f17c/disk-13d88ac5.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/fb496feed171/vmlinux-13d88ac5.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/f4da22719ffa/bzImage-13d88ac5.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+26eedf3631650972f17c@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> executing program
> BUG: memory leak
> unreferenced object 0xffff8881009b40a8 (size 8):
>   comm "syz-executor225", pid 5035, jiffies 4294944336 (age 13.730s)
>   hex dump (first 8 bytes):
>     2e 00 00 00 00 00 00 00                          ........
>   backtrace:
>     [<ffffffff8163331d>] kmemleak_alloc_recursive include/linux/kmemleak.h:42 [inline]
>     [<ffffffff8163331d>] slab_post_alloc_hook mm/slab.h:766 [inline]
>     [<ffffffff8163331d>] slab_alloc_node mm/slub.c:3478 [inline]
>     [<ffffffff8163331d>] __kmem_cache_alloc_node+0x2dd/0x3f0 mm/slub.c:3517
>     [<ffffffff8157e57c>] __do_kmalloc_node mm/slab_common.c:1006 [inline]
>     [<ffffffff8157e57c>] __kmalloc_node_track_caller+0x4c/0x150 mm/slab_common.c:1027
>     [<ffffffff8156da4c>] kstrdup+0x3c/0x70 mm/util.c:62
>     [<ffffffff81d0438a>] ovl_parse_param_lowerdir fs/overlayfs/params.c:496 [inline]
>     [<ffffffff81d0438a>] ovl_parse_param+0x70a/0xc70 fs/overlayfs/params.c:576
>     [<ffffffff8170542b>] vfs_parse_fs_param+0xfb/0x190 fs/fs_context.c:146
>     [<ffffffff81705556>] vfs_parse_fs_string+0x96/0xd0 fs/fs_context.c:188
>     [<ffffffff8170566f>] vfs_parse_monolithic_sep+0xdf/0x130 fs/fs_context.c:230
>     [<ffffffff816dff08>] do_new_mount fs/namespace.c:3333 [inline]
>     [<ffffffff816dff08>] path_mount+0xc48/0x10d0 fs/namespace.c:3664
>     [<ffffffff816e0b41>] do_mount fs/namespace.c:3677 [inline]
>     [<ffffffff816e0b41>] __do_sys_mount fs/namespace.c:3886 [inline]
>     [<ffffffff816e0b41>] __se_sys_mount fs/namespace.c:3863 [inline]
>     [<ffffffff816e0b41>] __x64_sys_mount+0x1a1/0x1f0 fs/namespace.c:3863
>     [<ffffffff84b67d8f>] do_syscall_x64 arch/x86/entry/common.c:51 [inline]
>     [<ffffffff84b67d8f>] do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:82
>     [<ffffffff84c0008b>] entry_SYSCALL_64_after_hwframe+0x63/0x6b
>
> BUG: memory leak
> unreferenced object 0xffff88814002d070 (size 8):
>   comm "syz-executor225", pid 5036, jiffies 4294944900 (age 8.090s)
>   hex dump (first 8 bytes):
>     2e 00 00 00 00 00 00 00                          ........
>   backtrace:
>     [<ffffffff8163331d>] kmemleak_alloc_recursive include/linux/kmemleak.h:42 [inline]
>     [<ffffffff8163331d>] slab_post_alloc_hook mm/slab.h:766 [inline]
>     [<ffffffff8163331d>] slab_alloc_node mm/slub.c:3478 [inline]
>     [<ffffffff8163331d>] __kmem_cache_alloc_node+0x2dd/0x3f0 mm/slub.c:3517
>     [<ffffffff8157e57c>] __do_kmalloc_node mm/slab_common.c:1006 [inline]
>     [<ffffffff8157e57c>] __kmalloc_node_track_caller+0x4c/0x150 mm/slab_common.c:1027
>     [<ffffffff8156da4c>] kstrdup+0x3c/0x70 mm/util.c:62
>     [<ffffffff81d0438a>] ovl_parse_param_lowerdir fs/overlayfs/params.c:496 [inline]
>     [<ffffffff81d0438a>] ovl_parse_param+0x70a/0xc70 fs/overlayfs/params.c:576
>     [<ffffffff8170542b>] vfs_parse_fs_param+0xfb/0x190 fs/fs_context.c:146
>     [<ffffffff81705556>] vfs_parse_fs_string+0x96/0xd0 fs/fs_context.c:188
>     [<ffffffff8170566f>] vfs_parse_monolithic_sep+0xdf/0x130 fs/fs_context.c:230
>     [<ffffffff816dff08>] do_new_mount fs/namespace.c:3333 [inline]
>     [<ffffffff816dff08>] path_mount+0xc48/0x10d0 fs/namespace.c:3664
>     [<ffffffff816e0b41>] do_mount fs/namespace.c:3677 [inline]
>     [<ffffffff816e0b41>] __do_sys_mount fs/namespace.c:3886 [inline]
>     [<ffffffff816e0b41>] __se_sys_mount fs/namespace.c:3863 [inline]
>     [<ffffffff816e0b41>] __x64_sys_mount+0x1a1/0x1f0 fs/namespace.c:3863
>     [<ffffffff84b67d8f>] do_syscall_x64 arch/x86/entry/common.c:51 [inline]
>     [<ffffffff84b67d8f>] do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:82
>     [<ffffffff84c0008b>] entry_SYSCALL_64_after_hwframe+0x63/0x6b
>
>

#syz test: https://github.com/amir73il/linux ovl-fixes