[syzbot] [hfs?] general protection fault in hfsplus_cat_write_inode

[syzbot] [hfs?] general protection fault in hfsplus_cat_write_inode

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    26ff969926a0 Merge tag 'rust-7.1' of git://git.kernel.org/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=123510ce580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bcb138057684c76a
dashboard link: https://syzkaller.appspot.com/bug?extid=c0ba772a362e70937dfb
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=163510ce580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=112bdb02580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8710bc1acc42/disk-26ff9699.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f03e7f936c8a/vmlinux-26ff9699.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ba58fa2f951e/bzImage-26ff9699.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/08271f11c795/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c0ba772a362e70937dfb@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 1024
hfsplus: xattr search failed
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
CPU: 0 UID: 0 PID: 6072 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:hfsplus_cat_write_inode+0xbe/0x8f0 fs/hfsplus/inode.c:637
Code: f3 f3 4a 89 44 33 51 4a 89 44 33 59 66 42 c7 44 33 61 f3 f3 42 c6 44 33 63 f3 e8 2d 77 23 ff 4d 8d 7d 28 4c 89 f8 48 c1 e8 03 <42> 80 3c 30 00 74 08 4c 89 ff e8 73 9b 89 ff 41 be 98 07 00 00 4d
RSP: 0018:ffffc900040f7880 EFLAGS: 00010206
RAX: 0000000000000005 RBX: 1ffff9200081ef14 RCX: ffff888028725b80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900040f7c10 R08: 0000000000000004 R09: 0000000000000004
R10: fffff5200081ef24 R11: fffffbfff1ed4f17 R12: 1ffff9200081ef8c
R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000028
FS:  0000555586e4a500(0000) GS:ffff888126332000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f427032f000 CR3: 0000000036c06000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 hfsplus_unlink+0x57a/0x930 fs/hfsplus/dir.c:435
 vfs_unlink+0x272/0x6d0 fs/namei.c:5476
 filename_unlinkat+0x3d3/0x610 fs/namei.c:5546
 __do_sys_unlink fs/namei.c:5581 [inline]
 __se_sys_unlink+0x2e/0x140 fs/namei.c:5578
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f464eabc819
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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd69795788 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 00007f464ed35fa0 RCX: 00007f464eabc819
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000200
RBP: 00007f464eb52c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f464ed35fac R14: 00007f464ed35fa0 R15: 00007f464ed35fa0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:hfsplus_cat_write_inode+0xbe/0x8f0 fs/hfsplus/inode.c:637
Code: f3 f3 4a 89 44 33 51 4a 89 44 33 59 66 42 c7 44 33 61 f3 f3 42 c6 44 33 63 f3 e8 2d 77 23 ff 4d 8d 7d 28 4c 89 f8 48 c1 e8 03 <42> 80 3c 30 00 74 08 4c 89 ff e8 73 9b 89 ff 41 be 98 07 00 00 4d
RSP: 0018:ffffc900040f7880 EFLAGS: 00010206
RAX: 0000000000000005 RBX: 1ffff9200081ef14 RCX: ffff888028725b80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900040f7c10 R08: 0000000000000004 R09: 0000000000000004
R10: fffff5200081ef24 R11: fffffbfff1ed4f17 R12: 1ffff9200081ef8c
R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000028
FS:  0000555586e4a500(0000) GS:ffff888126332000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f427032f000 CR3: 0000000036c06000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	f3 f3 4a 89 44 33 51 	repz xrelease mov %rax,0x51(%rbx,%r14,1)
   7:	4a 89 44 33 59       	mov    %rax,0x59(%rbx,%r14,1)
   c:	66 42 c7 44 33 61 f3 	movw   $0xf3f3,0x61(%rbx,%r14,1)
  13:	f3
  14:	42 c6 44 33 63 f3    	movb   $0xf3,0x63(%rbx,%r14,1)
  1a:	e8 2d 77 23 ff       	call   0xff23774c
  1f:	4d 8d 7d 28          	lea    0x28(%r13),%r15
  23:	4c 89 f8             	mov    %r15,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 ff             	mov    %r15,%rdi
  34:	e8 73 9b 89 ff       	call   0xff899bac
  39:	41 be 98 07 00 00    	mov    $0x798,%r14d
  3f:	4d                   	rex.WRB


---
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

Forwarded: [PATCH] hfsplus: fix ignored error return in hfsplus_delete_cat

[syzbot]

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

***

Subject: [PATCH] hfsplus: fix ignored error return in hfsplus_delete_cat
Author: kartikey406@gmail.com

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

hfsplus_delete_cat() calls hfsplus_delete_all_attrs() to remove all
extended attributes associated with a catalog entry, but silently
discards its return value. When the xattr deletion fails due to
filesystem corruption (as in a crafted image reported by syzbot),
hfsplus_delete_cat() returns 0 (success) to hfsplus_unlink().

hfsplus_unlink() then proceeds to call hfsplus_cat_write_inode() on
the inode in a corrupt, half-deleted state. Inside that function, if
HFSPLUS_IS_RSRC() is true but rsrc_inode was never properly set,
main_inode is assigned NULL. The subsequent dereference of
main_inode->i_nlink triggers a general protection fault, caught by
KASAN as a null-ptr-deref at offset 0x28.

Fix this by capturing the return value of hfsplus_delete_all_attrs()
and propagating genuine errors back to the caller. -ENOENT is
excluded since it signals normal loop termination (no more xattrs
left to delete) and is not an error condition.

Reported-by: syzbot+c0ba772a362e70937dfb@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=c0ba772a362e70937dfb
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
---
 fs/hfsplus/catalog.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/hfsplus/catalog.c b/fs/hfsplus/catalog.c
index 02c1eee4a4b8..adbaeabc06ab 100644
--- a/fs/hfsplus/catalog.c
+++ b/fs/hfsplus/catalog.c
@@ -421,8 +421,14 @@ int hfsplus_delete_cat(u32 cnid, struct inode *dir, const struct qstr *str)
 	hfsplus_mark_inode_dirty(dir, HFSPLUS_I_CAT_DIRTY);
 
 	if (type == HFSPLUS_FILE || type == HFSPLUS_FOLDER) {
-		if (HFSPLUS_SB(sb)->attr_tree)
-			hfsplus_delete_all_attrs(dir, cnid);
+		if (HFSPLUS_SB(sb)->attr_tree) {
+			int attr_err = hfsplus_delete_all_attrs(dir, cnid);
+			if (attr_err && attr_err != -ENOENT) {
+				pr_err("hfsplus: failed to delete xattrs for cnid %u: %d\n",
+				       cnid, attr_err);
+				err = attr_err;
+			}
+		}
 	}
 
 out:
-- 
2.43.0

Forwarded: [PATCH] hfsplus: fix null-ptr-deref in hfsplus_cat_write_inode

[syzbot]

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

***

Subject: [PATCH] hfsplus: fix null-ptr-deref in hfsplus_cat_write_inode
Author: kartikey406@gmail.com

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

When a corrupt HFS+ image is mounted where the hidden directory is
absent, hfsplus_fill_super() handles -ENOENT from
hfsplus_get_hidden_dir_entry() silently and continues with
sbi->hidden_dir left as NULL.

hfsplus_link() and hfsplus_unlink() call
hfsplus_cat_write_inode(sbi->hidden_dir) unconditionally without
checking whether hidden_dir is NULL, triggering a general protection
fault caught by KASAN as a null-ptr-deref at offset 0x28.

Other call sites in dir.c already guard against this by checking
hidden_dir for NULL before use. Apply the same guard to the two
unprotected call sites in hfsplus_link() and hfsplus_unlink().

Reported-by: syzbot+c0ba772a362e70937dfb@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=c0ba772a362e70937dfb
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
---
 fs/hfsplus/dir.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/fs/hfsplus/dir.c b/fs/hfsplus/dir.c
index d559bf8625f8..a7feef53d8cb 100644
--- a/fs/hfsplus/dir.c
+++ b/fs/hfsplus/dir.c
@@ -362,9 +362,11 @@ static int hfsplus_link(struct dentry *src_dentry, struct inode *dst_dir,
 	if (res)
 		goto out;
 
-	res = hfsplus_cat_write_inode(sbi->hidden_dir);
-	if (res)
-		goto out;
+	if (sbi->hidden_dir) {
+		res = hfsplus_cat_write_inode(sbi->hidden_dir);
+		if (res)
+			goto out;
+	}
 
 	res = hfsplus_cat_write_inode(inode);
 
@@ -431,11 +433,10 @@ static int hfsplus_unlink(struct inode *dir, struct dentry *dentry)
 out:
 	if (!res) {
 		res = hfsplus_cat_write_inode(dir);
-		if (!res) {
+		if (!res && sbi->hidden_dir)
 			res = hfsplus_cat_write_inode(sbi->hidden_dir);
-			if (!res)
-				res = hfsplus_cat_write_inode(inode);
-		}
+		if (!res)
+			res = hfsplus_cat_write_inode(inode);
 	}
 
 	mutex_unlock(&sbi->vh_mutex);
-- 
2.43.0