[syzbot] [overlayfs?] memory leak in ovl_parse_param

[syzbot] [overlayfs?] memory leak in ovl_parse_param

[syzbot]

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@syzkaller.appspotmail.com

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



---
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If the report is already addressed, let syzbot know by replying with:
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Re: [syzbot] [PATCH] Test memory leak in ovl_parse_param

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.

***

Subject: [PATCH] Test memory leak in ovl_parse_param
Author: eadavis@qq.com

please test memory leak in ovl_parse_param

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 13d88ac54ddd

diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
index ddab9ea267d1..735ae0db404a 100644
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -530,6 +530,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
 	return 0;
 
 out_put:
+	ctr->nr = nr;
 	ovl_reset_lowerdirs(ctx);
 
 out_err:

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

[Amir Goldstein]

On Sun, Nov 12, 2023 at 6:18 AM syzbot
<syzbot+26eedf3631650972f17c@syzkaller.appspotmail.com> 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@syzkaller.appspotmail.com
>
> 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

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

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
memory leak in ovl_parse_param

BUG: memory leak
unreferenced object 0xffff88814002d0c8 (size 8):
  comm "syz-executor.0", pid 5498, jiffies 4294944229 (age 12.660s)
  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
    [<ffffffff81d0424e>] ovl_parse_param_lowerdir fs/overlayfs/params.c:496 [inline]
    [<ffffffff81d0424e>] ovl_parse_param+0x70e/0xc60 fs/overlayfs/params.c:576
    [<ffffffff817053ab>] vfs_parse_fs_param+0xfb/0x190 fs/fs_context.c:146
    [<ffffffff817054d6>] vfs_parse_fs_string+0x96/0xd0 fs/fs_context.c:188
    [<ffffffff817055ef>] vfs_parse_monolithic_sep+0xdf/0x130 fs/fs_context.c:230
    [<ffffffff816dfe88>] do_new_mount fs/namespace.c:3333 [inline]
    [<ffffffff816dfe88>] path_mount+0xc48/0x10d0 fs/namespace.c:3664
    [<ffffffff816e0ac1>] do_mount fs/namespace.c:3677 [inline]
    [<ffffffff816e0ac1>] __do_sys_mount fs/namespace.c:3886 [inline]
    [<ffffffff816e0ac1>] __se_sys_mount fs/namespace.c:3863 [inline]
    [<ffffffff816e0ac1>] __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 0xffff8881009ec0c8 (size 8):
  comm "syz-executor.0", pid 5752, jiffies 4294944765 (age 7.300s)
  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
    [<ffffffff81d0424e>] ovl_parse_param_lowerdir fs/overlayfs/params.c:496 [inline]
    [<ffffffff81d0424e>] ovl_parse_param+0x70e/0xc60 fs/overlayfs/params.c:576
    [<ffffffff817053ab>] vfs_parse_fs_param+0xfb/0x190 fs/fs_context.c:146
    [<ffffffff817054d6>] vfs_parse_fs_string+0x96/0xd0 fs/fs_context.c:188
    [<ffffffff817055ef>] vfs_parse_monolithic_sep+0xdf/0x130 fs/fs_context.c:230
    [<ffffffff816dfe88>] do_new_mount fs/namespace.c:3333 [inline]
    [<ffffffff816dfe88>] path_mount+0xc48/0x10d0 fs/namespace.c:3664
    [<ffffffff816e0ac1>] do_mount fs/namespace.c:3677 [inline]
    [<ffffffff816e0ac1>] __do_sys_mount fs/namespace.c:3886 [inline]
    [<ffffffff816e0ac1>] __se_sys_mount fs/namespace.c:3863 [inline]
    [<ffffffff816e0ac1>] __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 0xffff8881009ec0e0 (size 8):
  comm "syz-executor.0", pid 5754, jiffies 4294944766 (age 7.290s)
  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
    [<ffffffff81d0424e>] ovl_parse_param_lowerdir fs/overlayfs/params.c:496 [inline]
    [<ffffffff81d0424e>] ovl_parse_param+0x70e/0xc60 fs/overlayfs/params.c:576
    [<ffffffff817053ab>] vfs_parse_fs_param+0xfb/0x190 fs/fs_context.c:146
    [<ffffffff817054d6>] vfs_parse_fs_string+0x96/0xd0 fs/fs_context.c:188
    [<ffffffff817055ef>] vfs_parse_monolithic_sep+0xdf/0x130 fs/fs_context.c:230
    [<ffffffff816dfe88>] do_new_mount fs/namespace.c:3333 [inline]
    [<ffffffff816dfe88>] path_mount+0xc48/0x10d0 fs/namespace.c:3664
    [<ffffffff816e0ac1>] do_mount fs/namespace.c:3677 [inline]
    [<ffffffff816e0ac1>] __do_sys_mount fs/namespace.c:3886 [inline]
    [<ffffffff816e0ac1>] __se_sys_mount fs/namespace.c:3863 [inline]
    [<ffffffff816e0ac1>] __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



Tested on:

commit:         3f653af2 ovl: fix memory leak in ovl_parse_param()
git tree:       https://github.com/amir73il/linux ovl-fixes
console output: https://syzkaller.appspot.com/x/log.txt?x=13a07ea7680000
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

Note: no patches were applied.

Re: [syzbot] [PATCH] Test memory leak in ovl_parse_param

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.

***

Subject: [PATCH] Test memory leak in ovl_parse_param
Author: eadavis@qq.com

please test memory leak in ovl_parse_param

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 13d88ac54ddd

diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
index ddab9ea267d1..735ae0db404a 100644
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -530,6 +530,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
 	return 0;
 
 out_put:
+	ctx->nr = nr;
 	ovl_reset_lowerdirs(ctx);
 
 out_err:

[PATCH] ovl: fix memory leak in ovl_parse_param

[Edward Adam Davis]

After failing to parse parameters in ovl_parse_param_lowerdir(), it is 
necessary to update ctx->nr with the correct nr before using 
ovl_reset_lowerdirs() to release l->name.

Reported-and-tested-by: syzbot+26eedf3631650972f17c@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 fs/overlayfs/params.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
index ddab9ea267d1..1f73f0173015 100644
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -530,6 +530,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
 	return 0;
 
 out_put:
+	ctx->nr = nr;
 	ovl_reset_lowerdirs(ctx);
 
 out_err:
-- 
2.25.1

Re: [PATCH] ovl: fix memory leak in ovl_parse_param

[Amir Goldstein]

On Sun, Nov 12, 2023 at 12:35 PM Edward Adam Davis <eadavis@qq.com> wrote:
>
> After failing to parse parameters in ovl_parse_param_lowerdir(), it is
> necessary to update ctx->nr with the correct nr before using
> ovl_reset_lowerdirs() to release l->name.
>
> Reported-and-tested-by: syzbot+26eedf3631650972f17c@syzkaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
>  fs/overlayfs/params.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
> index ddab9ea267d1..1f73f0173015 100644
> --- a/fs/overlayfs/params.c
> +++ b/fs/overlayfs/params.c
> @@ -530,6 +530,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
>         return 0;
>
>  out_put:
> +       ctx->nr = nr;
>         ovl_reset_lowerdirs(ctx);
>
>  out_err:
> --
> 2.25.1
>

Thanks for the patch!

I prefer to fix it by eliminating the local vars instead of
syncing with them:

I've kept your commit message and tagged you as Co-authored-by:
https://github.com/amir73il/linux/commit/97d58994e880ccb19e1b9b935928538903fca41c

Thanks,
Amir.

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

[Amir Goldstein]

On Sun, Nov 12, 2023 at 11:10 AM Amir Goldstein <amir73il@gmail.com> wrote:
>
> On Sun, Nov 12, 2023 at 6:18 AM syzbot
> <syzbot+26eedf3631650972f17c@syzkaller.appspotmail.com> 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@syzkaller.appspotmail.com
> >
> > 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

Please test take #2:
#syz test: https://github.com/amir73il/linux ovl-fixes

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

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+26eedf3631650972f17c@syzkaller.appspotmail.com

Tested on:

commit:         97d58994 ovl: fix memory leak in ovl_parse_param()
git tree:       https://github.com/amir73il/linux ovl-fixes
console output: https://syzkaller.appspot.com/x/log.txt?x=12394b97680000
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

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.