[syzbot] [overlayfs?] WARNING in ovl_listxattr

[syzbot] [overlayfs?] WARNING in ovl_listxattr

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    e9565e23cd89 Merge tag 'sched_ext-for-6.15-rc6-fixes' of g..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=15ee8f68580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5929ac65be9baf3c
dashboard link: https://syzkaller.appspot.com/bug?extid=4125590f2a9f5b3cdf43
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12cb6af4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1301f670580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/88b9a7ce7297/disk-e9565e23.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6ef1e04f11ea/vmlinux-e9565e23.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dfb61d29ee21/bzImage-e9565e23.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4125590f2a9f5b3cdf43@syzkaller.appspotmail.com

WARNING: The mand mount option has been deprecated and
         and is ignored by this kernel. Remove the mand
         option from the mount to silence this warning.
=======================================================
------------[ cut here ]------------
WARNING: CPU: 0 PID: 5827 at fs/overlayfs/xattrs.c:136 ovl_listxattr+0x3a3/0x400 fs/overlayfs/xattrs.c:136
Modules linked in:
CPU: 0 UID: 0 PID: 5827 Comm: syz-executor209 Not tainted 6.15.0-rc6-syzkaller-00047-ge9565e23cd89 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:ovl_listxattr+0x3a3/0x400 fs/overlayfs/xattrs.c:136
Code: d5 f3 fe e9 47 ff ff ff e8 da 06 94 fe 4c 89 f8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 be 06 94 fe 90 <0f> 0b 90 49 c7 c7 fb ff ff ff eb d7 e8 ac 06 94 fe 90 0f 0b 90 e9
RSP: 0018:ffffc9000440fdb8 EFLAGS: 00010293
RAX: ffffffff832bea42 RBX: ffff888020aec700 RCX: ffff88802faf5a00
RDX: 0000000000000000 RSI: 0000000000000011 RDI: 0000000000000012
RBP: ffff88823bf5cf01 R08: ffff8880335691d3 R09: 1ffff110066ad23a
R10: dffffc0000000000 R11: ffffed10066ad23b R12: ffffffffffffffff
R13: 0000000000000012 R14: ffff8880687d7820 R15: 0000000000000011
FS:  000055558015f380(0000) GS:ffff8881260fb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 000000007f130000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 vfs_listxattr fs/xattr.c:493 [inline]
 listxattr+0x10d/0x2a0 fs/xattr.c:924
 filename_listxattr fs/xattr.c:958 [inline]
 path_listxattrat+0x179/0x390 fs/xattr.c:988
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcb6cb2da39
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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:00007ffdbfef0558 EFLAGS: 00000246 ORIG_RAX: 00000000000000c3
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007fcb6cb2da39
RDX: 00000000000000b6 RSI: 0000200000000200 RDI: 00002000000001c0
RBP: 0000200000000180 R08: 0000000000000006 R09: 0000000000000006
R10: 0000200000000300 R11: 0000000000000246 R12: 00007fcb6cb7c17c
R13: 00007fcb6cb77082 R14: 0000000000000001 R15: 0000000000000001
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

Re: [syzbot] Re: [syzbot] [overlayfs?] WARNING in ovl_listxattr

[syzbot]

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

***

Subject: Re: [syzbot] [overlayfs?] WARNING in ovl_listxattr
Author: lizhi.xu@windriver.com

#syz test

diff --git a/fs/overlayfs/xattrs.c b/fs/overlayfs/xattrs.c
index 88055deca936..69e17db853f5 100644
--- a/fs/overlayfs/xattrs.c
+++ b/fs/overlayfs/xattrs.c
@@ -122,6 +122,7 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
 	old_cred = ovl_override_creds(dentry->d_sb);
 	res = vfs_listxattr(realdentry, list, size);
 	ovl_revert_creds(old_cred);
+	printk("buf: %s, size: %lu, res: %ld, %s\n", list, size, res, __func__);
 	if (res <= 0 || size == 0)
 		return res;
 
@@ -131,6 +132,7 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
 	/* filter out private xattrs */
 	for (s = list, len = res; len;) {
 		size_t slen = strnlen(s, len) + 1;
+		printk("s: %s, len: %lu, slen: %lu, %s\n", s, len, slen, __func__);
 
 		/* underlying fs providing us with an broken xattr list? */
 		if (WARN_ON(slen > len))

Re: [syzbot] [overlayfs?] WARNING in ovl_listxattr

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in ovl_listxattr

WARNING: The mand mount option has been deprecated and
         and is ignored by this kernel. Remove the mand
         option from the mount to silence this warning.
=======================================================
buf: system.posix_acl_access, size: 182, res: 17, ovl_listxattr
s: system.posix_acl_access, len: 17, slen: 18, ovl_listxattr
------------[ cut here ]------------
WARNING: CPU: 1 PID: 6633 at fs/overlayfs/xattrs.c:138 ovl_listxattr+0x3db/0x430 fs/overlayfs/xattrs.c:138
Modules linked in:
CPU: 1 UID: 0 PID: 6633 Comm: syz.0.16 Not tainted 6.16.0-rc1-syzkaller-g2c4a1f3fe03e-dirty #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:ovl_listxattr+0x3db/0x430 fs/overlayfs/xattrs.c:138
Code: 05 f2 fe e9 47 ff ff ff e8 02 b9 90 fe 4c 89 f8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 e6 b8 90 fe 90 <0f> 0b 90 49 c7 c7 fb ff ff ff eb d7 e8 d4 b8 90 fe 90 0f 0b 90 e9
RSP: 0018:ffffc900033a7d98 EFLAGS: 00010293
RAX: ffffffff832f950a RBX: ffff888077ba4200 RCX: ffff88802d620000
RDX: 0000000000000000 RSI: 0000000000000011 RDI: 0000000000000012
RBP: ffff88802a27de01 R08: ffffc900033a7ac7 R09: 1ffff92000674f58
R10: dffffc0000000000 R11: fffff52000674f59 R12: ffffffffffffffff
R13: 0000000000000012 R14: ffff8880787a3c88 R15: 0000000000000011
FS:  00007f48fba146c0(0000) GS:ffff888125d86000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 000000007c3f0000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 vfs_listxattr fs/xattr.c:493 [inline]
 listxattr+0x10a/0x2a0 fs/xattr.c:924
 filename_listxattr fs/xattr.c:958 [inline]
 path_listxattrat+0x179/0x3a0 fs/xattr.c:988
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f48fab8e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f48fba14038 EFLAGS: 00000246 ORIG_RAX: 00000000000000c3
RAX: ffffffffffffffda RBX: 00007f48fadb5fa0 RCX: 00007f48fab8e969
RDX: 00000000000000b6 RSI: 0000200000000200 RDI: 00002000000001c0
RBP: 00007f48fac10ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f48fadb5fa0 R15: 00007ffea266aa98
 </TASK>


Tested on:

commit:         2c4a1f3f Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15676e0c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=162faeb2d1eaefb4
dashboard link: https://syzkaller.appspot.com/bug?extid=4125590f2a9f5b3cdf43
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
patch:          https://syzkaller.appspot.com/x/patch.diff?x=117b6e0c580000

Re: [syzbot] [overlayfs?] WARNING in ovl_listxattr

[Edward Adam Davis]

#syz test

diff --git a/fs/xattr.c b/fs/xattr.c
index 8ec5b0204bfd..1f55b98ae275 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -491,6 +491,7 @@ vfs_listxattr(struct dentry *dentry, char *list, size_t size)
 
 	if (inode->i_op->listxattr) {
 		error = inode->i_op->listxattr(dentry, list, size);
+		printk("buf: %s, size: %lu, res: %ld, sb: %s, %s\n", list, size, error, inode->i_sb->s_type->name, __func__);
 	} else {
 		error = security_inode_listsecurity(inode, list, size);
 		if (size && error > size)
@@ -1466,12 +1467,14 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
 	int err = 0;
 
 	err = posix_acl_listxattr(inode, &buffer, &remaining_size);
+	printk("inode: %p, buf: %s, size: %lu, res: %d, %s\n", inode, buffer, size, err, __func__);
 	if (err)
-		return err;
+		goto out;
 
 	err = security_inode_listsecurity(inode, buffer, remaining_size);
+	printk("2inode: %p, buf: %s, size: %lu, res: %d, %s\n", inode, buffer, size, err, __func__);
 	if (err < 0)
-		return err;
+		goto out;
 
 	if (buffer) {
 		if (remaining_size < err)
@@ -1498,7 +1501,12 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
 	}
 	read_unlock(&xattrs->lock);
 
-	return err ? err : size - remaining_size;
+	printk("3inode: %p, buf: %s, size: %lu, res: %d, remaining_size: %ld, %s\n", inode, buffer, size, err, remaining_size, __func__);
+	err = err ? err : size - remaining_size;
+	if (err > 0 && err < 24)
+		err = -ERANGE;
+out:
+	return err;
 }
 
 /**

Re: [syzbot] [overlayfs?] WARNING in ovl_listxattr

[syzbot]

Hello,

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

Reported-by: syzbot+4125590f2a9f5b3cdf43@syzkaller.appspotmail.com
Tested-by: syzbot+4125590f2a9f5b3cdf43@syzkaller.appspotmail.com

Tested on:

commit:         2c4a1f3f Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=160fa10c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=162faeb2d1eaefb4
dashboard link: https://syzkaller.appspot.com/bug?extid=4125590f2a9f5b3cdf43
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15b4ee0c580000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [overlayfs?] WARNING in ovl_listxattr

[Edward Adam Davis]

#syz test

diff --git a/fs/xattr.c b/fs/xattr.c
index 8ec5b0204bfd..49bbce356e27 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -491,6 +491,7 @@ vfs_listxattr(struct dentry *dentry, char *list, size_t size)
 
 	if (inode->i_op->listxattr) {
 		error = inode->i_op->listxattr(dentry, list, size);
+		printk("buf: %s, size: %lu, res: %ld, sb: %s, %s\n", list, size, error, inode->i_sb->s_type->name, __func__);
 	} else {
 		error = security_inode_listsecurity(inode, list, size);
 		if (size && error > size)
@@ -1466,12 +1467,14 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
 	int err = 0;
 
 	err = posix_acl_listxattr(inode, &buffer, &remaining_size);
+	printk("inode: %p, buf: %s, size: %lu, res: %d, %s\n", inode, buffer, size, err, __func__);
 	if (err)
-		return err;
+		goto out;
 
 	err = security_inode_listsecurity(inode, buffer, remaining_size);
+	printk("2inode: %p, buf: %s, size: %lu, res: %d, %s\n", inode, buffer, size, err, __func__);
 	if (err < 0)
-		return err;
+		goto out;
 
 	if (buffer) {
 		if (remaining_size < err)
@@ -1498,7 +1501,13 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
 	}
 	read_unlock(&xattrs->lock);
 
-	return err ? err : size - remaining_size;
+	printk("3inode: %p, buf: %s, size: %lu, res: %d, remaining_size: %ld, %s\n", inode, buffer, size, err, remaining_size, __func__);
+	if (IS_POSIXACL(inode) && !err && size - remaining_size < 24)
+		;//err = -ERANGE;
+	else
+		err = err ? err : size - remaining_size;
+out:
+	return err;
 }
 
 /**

Re: [syzbot] [overlayfs?] WARNING in ovl_listxattr

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in ovl_listxattr

3inode: ffff888078108508, buf: , size: 182, res: 17, remaining_size: 116, simple_xattr_list
buf: system.posix_acl_access, size: 182, res: 17, sb: sysfs, vfs_listxattr
------------[ cut here ]------------
WARNING: CPU: 0 PID: 6609 at fs/overlayfs/xattrs.c:136 ovl_listxattr+0x3a3/0x400 fs/overlayfs/xattrs.c:136
Modules linked in:
CPU: 0 UID: 0 PID: 6609 Comm: syz.0.16 Not tainted 6.16.0-rc1-syzkaller-g2c4a1f3fe03e-dirty #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:ovl_listxattr+0x3a3/0x400 fs/overlayfs/xattrs.c:136
Code: 08 f2 fe e9 47 ff ff ff e8 2a bc 90 fe 4c 89 f8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 84 17 32 08 cc e8 0e bc 90 fe 90 <0f> 0b 90 49 c7 c7 fb ff ff ff eb d7 e8 fc bb 90 fe 90 0f 0b 90 e9
RSP: 0018:ffffc90002f67d98 EFLAGS: 00010293
RAX: ffffffff832fa1e2 RBX: ffff888029d53400 RCX: ffff888025afda00
RDX: 0000000000000000 RSI: 0000000000000011 RDI: 0000000000000012
RBP: ffff888030fa9001 R08: ffffc90002f67a87 R09: 1ffff920005ecf50
R10: dffffc0000000000 R11: fffff520005ecf51 R12: ffffffffffffffff
R13: 0000000000000012 R14: ffff88807afcfc88 R15: 0000000000000011
FS:  00007fe253dad6c0(0000) GS:ffff888125c86000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 00000000748d2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 vfs_listxattr fs/xattr.c:493 [inline]
 listxattr+0x26d/0x320 fs/xattr.c:925
 filename_listxattr fs/xattr.c:959 [inline]
 path_listxattrat+0x179/0x3a0 fs/xattr.c:989
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe252f8e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe253dad038 EFLAGS: 00000246 ORIG_RAX: 00000000000000c3
RAX: ffffffffffffffda RBX: 00007fe2531b5fa0 RCX: 00007fe252f8e969
RDX: 00000000000000b6 RSI: 0000200000000200 RDI: 00002000000001c0
RBP: 00007fe253010ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe2531b5fa0 R15: 00007ffedfdb19e8
 </TASK>


Tested on:

commit:         2c4a1f3f Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=112be60c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=162faeb2d1eaefb4
dashboard link: https://syzkaller.appspot.com/bug?extid=4125590f2a9f5b3cdf43
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
patch:          https://syzkaller.appspot.com/x/patch.diff?x=14a2d9d4580000

Re: [syzbot] [overlayfs?] WARNING in ovl_listxattr

[Edward Adam Davis]

#syz test

diff --git a/fs/xattr.c b/fs/xattr.c
index 8ec5b0204bfd..3751c9306274 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -491,6 +491,7 @@ vfs_listxattr(struct dentry *dentry, char *list, size_t size)
 
 	if (inode->i_op->listxattr) {
 		error = inode->i_op->listxattr(dentry, list, size);
+		printk("buf: %s, size: %lu, res: %ld, sb: %s, %s\n", list, size, error, inode->i_sb->s_type->name, __func__);
 	} else {
 		error = security_inode_listsecurity(inode, list, size);
 		if (size && error > size)
@@ -1466,12 +1467,14 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
 	int err = 0;
 
 	err = posix_acl_listxattr(inode, &buffer, &remaining_size);
+	printk("inode: %p, buf: %s, size: %lu, res: %d, remaining_size: %ld, %s\n", inode, buffer, size, err, remaining_size, __func__);
 	if (err)
-		return err;
+		goto out;
 
 	err = security_inode_listsecurity(inode, buffer, remaining_size);
+	printk("2inode: %p, buf: %s, size: %lu, res: %d, remaining_size: %ld, %s\n", inode, buffer, size, err, remaining_size, __func__);
 	if (err < 0)
-		return err;
+		goto out;
 
 	if (buffer) {
 		if (remaining_size < err)
@@ -1479,6 +1482,7 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
 		buffer += err;
 	}
 	remaining_size -= err;
+	err = 0;
 
 	read_lock(&xattrs->lock);
 	for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) {
@@ -1498,6 +1502,8 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
 	}
 	read_unlock(&xattrs->lock);
 
+	printk("3inode: %p, buf: %s, size: %lu, res: %d, remaining_size: %ld, %s\n", inode, buffer, size, err, remaining_size, __func__);
+out:
 	return err ? err : size - remaining_size;
 }
 

Re: [syzbot] [overlayfs?] WARNING in ovl_listxattr

[syzbot]

Hello,

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

Reported-by: syzbot+4125590f2a9f5b3cdf43@syzkaller.appspotmail.com
Tested-by: syzbot+4125590f2a9f5b3cdf43@syzkaller.appspotmail.com

Tested on:

commit:         2c4a1f3f Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12b4ed70580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=162faeb2d1eaefb4
dashboard link: https://syzkaller.appspot.com/bug?extid=4125590f2a9f5b3cdf43
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1524ed70580000

Note: testing is done by a robot and is best-effort only.

[PATCH] fs/xattr: reset err to 0 after get security.* xattrs

[Edward Adam Davis]

After successfully getting "security.SMACK64", err is not reset to 0, which
causes simple_xattr_list() to return 17, which is much smaller than the
actual buffer size..

After updating err to remaining_size, reset err to 0 to avoid returning an
inappropriate buffer size.

Fixes: 8b0ba61df5a1 ("fs/xattr.c: fix simple_xattr_list to always include security.* xattrs")
Reported-by: syzbot+4125590f2a9f5b3cdf43@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=4125590f2a9f5b3cdf43
Tested-by: syzbot+4125590f2a9f5b3cdf43@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 fs/xattr.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/xattr.c b/fs/xattr.c
index 8ec5b0204bfd..600ae97969cf 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -1479,6 +1479,7 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
 		buffer += err;
 	}
 	remaining_size -= err;
+	err = 0;
 
 	read_lock(&xattrs->lock);
 	for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) {
-- 
2.43.0

Re: [PATCH] fs/xattr: reset err to 0 after get security.* xattrs

[Stephen Smalley]

On Thu, Jun 12, 2025 at 11:01 AM Edward Adam Davis <eadavis@qq.com> wrote:
>
> After successfully getting "security.SMACK64", err is not reset to 0, which
> causes simple_xattr_list() to return 17, which is much smaller than the
> actual buffer size..
>
> After updating err to remaining_size, reset err to 0 to avoid returning an
> inappropriate buffer size.
>
> Fixes: 8b0ba61df5a1 ("fs/xattr.c: fix simple_xattr_list to always include security.* xattrs")
> Reported-by: syzbot+4125590f2a9f5b3cdf43@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=4125590f2a9f5b3cdf43
> Tested-by: syzbot+4125590f2a9f5b3cdf43@syzkaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>

Already fixed on vfs/vfs.fixes, see:
https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git/commit/?h=vfs.fixes&id=800d0b9b6a8b1b354637b4194cc167ad1ce2bdd3

> ---
>  fs/xattr.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/fs/xattr.c b/fs/xattr.c
> index 8ec5b0204bfd..600ae97969cf 100644
> --- a/fs/xattr.c
> +++ b/fs/xattr.c
> @@ -1479,6 +1479,7 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
>                 buffer += err;
>         }
>         remaining_size -= err;
> +       err = 0;
>
>         read_lock(&xattrs->lock);
>         for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) {
> --
> 2.43.0
>

Re: [syzbot] [overlayfs?] WARNING in ovl_listxattr

[syzbot]

syzbot suspects this issue was fixed by commit:

commit 800d0b9b6a8b1b354637b4194cc167ad1ce2bdd3
Author: Stephen Smalley <stephen.smalley.work@gmail.com>
Date:   Thu Jun 5 16:51:16 2025 +0000

    fs/xattr.c: fix simple_xattr_list()

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=173de382580000
start commit:   e9565e23cd89 Merge tag 'sched_ext-for-6.15-rc6-fixes' of g..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=5929ac65be9baf3c
dashboard link: https://syzkaller.appspot.com/bug?extid=4125590f2a9f5b3cdf43
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12cb6af4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1301f670580000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: fs/xattr.c: fix simple_xattr_list()

For information about bisection process see: https://goo.gl/tpsmEJ#bisection