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

[syzbot <syzbot+c0ba772a362e70937dfb@syzkaller.appspotmail.com>]

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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