From: David Wei dw@davidwei.uk
[ Upstream commit 4720f9707c783f642332dee3d56dccaefa850e42 ]
Strings from the kernel are guaranteed to be null terminated and ynl_attr_validate() checks for this. But it doesn't check if the string has a len of 0, which would cause problems when trying to access data[len - 1]. Fix this by checking that len is positive.
Signed-off-by: David Wei dw@davidwei.uk Link: https://patch.msgid.link/20250503043050.861238-1-dw@davidwei.uk Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/net/ynl/lib/ynl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/net/ynl/lib/ynl.c b/tools/net/ynl/lib/ynl.c index ae61ae5b02bf8..0871f86c6b666 100644 --- a/tools/net/ynl/lib/ynl.c +++ b/tools/net/ynl/lib/ynl.c @@ -368,7 +368,7 @@ int ynl_attr_validate(struct ynl_parse_arg *yarg, const struct nlattr *attr) "Invalid attribute (binary %s)", policy->name); return -1; case YNL_PT_NUL_STR: - if ((!policy->len || len <= policy->len) && !data[len - 1]) + if (len && (!policy->len || len <= policy->len) && !data[len - 1]) break; yerr(yarg->ys, YNL_ERROR_ATTR_INVALID, "Invalid attribute (string %s)", policy->name);