[PATCH] hfsplus: Return null terminated string from hfsplus_uni2asc()

[PATCH] hfsplus: Return null terminated string from hfsplus_uni2asc()

[Aaro Mäkinen]

In case hfsplus_uni2asc() is called with reused buffer there is a
possibility that the buffer contains remains of the last string and the
null character is only after that. This can and has caused problems in
functions that call hfsplus_uni2asc().

Also correct the error handling for call to copy_name() where the above
problem caused error to be not passed in hfsplus_listxattr().

Fixes: 7dcbf17e3f91 ("hfsplus: refactor copy_name to not use strncpy")
Signed-off-by: Aaro Mäkinen <aaro@tuxera.com>
Reviewed-by: Anton Altaparmakov <anton@tuxera.com>
---
 fs/hfsplus/unicode.c |  1 +
 fs/hfsplus/xattr.c   | 13 ++++++++++---
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/fs/hfsplus/unicode.c b/fs/hfsplus/unicode.c
index 73342c925a4b..1f122e3c9583 100644
--- a/fs/hfsplus/unicode.c
+++ b/fs/hfsplus/unicode.c
@@ -246,6 +246,7 @@ int hfsplus_uni2asc(struct super_block *sb,
 	res = 0;
 out:
 	*len_p = (char *)op - astr;
+	*op = '\0';
 	return res;
 }
 
diff --git a/fs/hfsplus/xattr.c b/fs/hfsplus/xattr.c
index 9a1a93e3888b..f20487ad4e8a 100644
--- a/fs/hfsplus/xattr.c
+++ b/fs/hfsplus/xattr.c
@@ -746,9 +746,16 @@ ssize_t hfsplus_listxattr(struct dentry *dentry, char *buffer, size_t size)
 			if (size < (res + name_len(strbuf, xattr_name_len))) {
 				res = -ERANGE;
 				goto end_listxattr;
-			} else
-				res += copy_name(buffer + res,
-						strbuf, xattr_name_len);
+			} else {
+				err = copy_name(buffer + res,
+					strbuf, xattr_name_len);
+				if (err < 0) {
+					res = err;
+					goto end_listxattr;
+				}
+				else
+					res += err;
+			}
 		}
 
 		if (hfs_brec_goto(&fd, 1))
-- 
2.43.0

Re: [PATCH] hfsplus: Return null terminated string from hfsplus_uni2asc()

[kernel test robot]

Hi,

Thanks for your patch.

FYI: kernel test robot notices the stable kernel rule is not satisfied.

The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#option-1

Rule: add the tag "Cc: stable@vger.kernel.org" in the sign-off area to have the patch automatically included in the stable tree.
Subject: [PATCH] hfsplus: Return null terminated string from hfsplus_uni2asc()
Link: https://lore.kernel.org/stable/20250325132947.55401-1-aaro%40tuxera.com

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https://github.com/intel/lkp-tests/wiki