[syzbot] [hfs?] KMSAN: uninit-value in hfsplus_listxattr (2)

[syzbot] [hfs?] KMSAN: uninit-value in hfsplus_listxattr (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    fec50db7033e Linux 6.9-rc3
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1467098d180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=13e7da432565d94c
dashboard link: https://syzkaller.appspot.com/bug?extid=01ade747b16e9c8030e0
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=138f4d8d180000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15763da9180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/901017b36ccc/disk-fec50db7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/16bfcf5618d3/vmlinux-fec50db7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dc9c5a1e7d02/bzImage-fec50db7.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/4dff8cc527ea/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+01ade747b16e9c8030e0@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 1024
=====================================================
BUG: KMSAN: uninit-value in strncmp+0x11e/0x180 lib/string.c:291
 strncmp+0x11e/0x180 lib/string.c:291
 hfsplus_listxattr+0x97d/0x1a60
 vfs_listxattr fs/xattr.c:493 [inline]
 listxattr+0x1f3/0x6b0 fs/xattr.c:840
 path_listxattr fs/xattr.c:864 [inline]
 __do_sys_listxattr fs/xattr.c:876 [inline]
 __se_sys_listxattr fs/xattr.c:873 [inline]
 __x64_sys_listxattr+0x16b/0x2f0 fs/xattr.c:873
 do_syscall_64+0xd5/0x1f0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:3804 [inline]
 slab_alloc_node mm/slub.c:3845 [inline]
 kmalloc_trace+0x578/0xba0 mm/slub.c:3992
 kmalloc include/linux/slab.h:628 [inline]
 hfsplus_listxattr+0x4cc/0x1a60 fs/hfsplus/xattr.c:701
 vfs_listxattr fs/xattr.c:493 [inline]
 listxattr+0x1f3/0x6b0 fs/xattr.c:840
 path_listxattr fs/xattr.c:864 [inline]
 __do_sys_listxattr fs/xattr.c:876 [inline]
 __se_sys_listxattr fs/xattr.c:873 [inline]
 __x64_sys_listxattr+0x16b/0x2f0 fs/xattr.c:873
 do_syscall_64+0xd5/0x1f0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

CPU: 0 PID: 5019 Comm: syz-executor940 Not tainted 6.9.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
=====================================================


---
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#syz undup

Re: [syzbot] [hfs?] KMSAN: uninit-value in hfsplus_listxattr (2)

[Edward Adam Davis]

please test uini in hfsplus_listxattr

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git fec50db7033e

diff --git a/fs/hfsplus/xattr.c b/fs/hfsplus/xattr.c
index 9c9ff6b8c6f7..858029b1c173 100644
--- a/fs/hfsplus/xattr.c
+++ b/fs/hfsplus/xattr.c
@@ -698,7 +698,7 @@ ssize_t hfsplus_listxattr(struct dentry *dentry, char *buffer, size_t size)
 		return err;
 	}
 
-	strbuf = kmalloc(NLS_MAX_CHARSET_SIZE * HFSPLUS_ATTR_MAX_STRLEN +
+	strbuf = kzalloc(NLS_MAX_CHARSET_SIZE * HFSPLUS_ATTR_MAX_STRLEN +
 			XATTR_MAC_OSX_PREFIX_LEN + 1, GFP_KERNEL);
 	if (!strbuf) {
 		res = -ENOMEM;

Re: [syzbot] [hfs?] KMSAN: uninit-value in hfsplus_listxattr (2)

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+01ade747b16e9c8030e0@syzkaller.appspotmail.com

Tested on:

commit:         fec50db7 Linux 6.9-rc3
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1451495b180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=13e7da432565d94c
dashboard link: https://syzkaller.appspot.com/bug?extid=01ade747b16e9c8030e0
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1613e213180000

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

[PATCH] hfsplus: fix uninit-value in hfsplus_listxattr

[Edward Adam Davis]

[syzbot reported]
BUG: KMSAN: uninit-value in strncmp+0x11e/0x180 lib/string.c:291
 strncmp+0x11e/0x180 lib/string.c:291
 hfsplus_listxattr+0x97d/0x1a60
 vfs_listxattr fs/xattr.c:493 [inline]
 listxattr+0x1f3/0x6b0 fs/xattr.c:840
 path_listxattr fs/xattr.c:864 [inline]
 __do_sys_listxattr fs/xattr.c:876 [inline]
 __se_sys_listxattr fs/xattr.c:873 [inline]
 __x64_sys_listxattr+0x16b/0x2f0 fs/xattr.c:873
 do_syscall_64+0xd5/0x1f0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:3804 [inline]
 slab_alloc_node mm/slub.c:3845 [inline]
 kmalloc_trace+0x578/0xba0 mm/slub.c:3992
 kmalloc include/linux/slab.h:628 [inline]
 hfsplus_listxattr+0x4cc/0x1a60 fs/hfsplus/xattr.c:701
 vfs_listxattr fs/xattr.c:493 [inline]
 listxattr+0x1f3/0x6b0 fs/xattr.c:840
 path_listxattr fs/xattr.c:864 [inline]
 __do_sys_listxattr fs/xattr.c:876 [inline]
 __se_sys_listxattr fs/xattr.c:873 [inline]
 __x64_sys_listxattr+0x16b/0x2f0 fs/xattr.c:873
 do_syscall_64+0xd5/0x1f0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a
[Fix]
When allocating memory to strbuf, initialize memory to 0.

Reported-and-tested-by: syzbot+01ade747b16e9c8030e0@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 fs/hfsplus/xattr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/hfsplus/xattr.c b/fs/hfsplus/xattr.c
index 9c9ff6b8c6f7..858029b1c173 100644
--- a/fs/hfsplus/xattr.c
+++ b/fs/hfsplus/xattr.c
@@ -698,7 +698,7 @@ ssize_t hfsplus_listxattr(struct dentry *dentry, char *buffer, size_t size)
 		return err;
 	}
 
-	strbuf = kmalloc(NLS_MAX_CHARSET_SIZE * HFSPLUS_ATTR_MAX_STRLEN +
+	strbuf = kzalloc(NLS_MAX_CHARSET_SIZE * HFSPLUS_ATTR_MAX_STRLEN +
 			XATTR_MAC_OSX_PREFIX_LEN + 1, GFP_KERNEL);
 	if (!strbuf) {
 		res = -ENOMEM;
-- 
2.43.0