[PATCH v3 3/4] fs: prevent integer overflow in sqfs_concat

[Timo tp Preißl]

An integer overflow in length calculation could lead to
under-allocation and buffer overcopy.

Signed-off-by: Timo tp Preißl <t.preissl at proton.me>
---
 fs/squashfs/sqfs.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/squashfs/sqfs.c b/fs/squashfs/sqfs.c
index 4d3d83b7587..f668c26472e 100644
--- a/fs/squashfs/sqfs.c
+++ b/fs/squashfs/sqfs.c
@@ -255,10 +255,14 @@ static char *sqfs_concat_tokens(char **token_list, int token_count)
 {
 	char *result;
 	int i, length = 0, offset = 0;
+	size_t alloc;
 
 	length = sqfs_get_tokens_length(token_list, token_count);
 
-	result = malloc(length + 1);
+	if (__builtin_add_overflow(length, 1, &alloc))
+		return 0;
+
+	result = malloc(alloc);
 	if (!result)
 		return NULL;
 
-- 
2.43.0