6.17-stable review patch. If anyone has any objections, please let me know.
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From: Petr Oros poros@redhat.com
[ Upstream commit 65f9c4c5888913c2cf5d2fc9454c83f9930d537d ]
The ynl_attr_put_str() function was not including the null terminator in the attribute length calculation. This caused kernel to reject CTRL_CMD_GETFAMILY requests with EINVAL: "Attribute failed policy validation".
For a 4-character family name like "dpll": - Sent: nla_len=8 (4 byte header + 4 byte string without null) - Expected: nla_len=9 (4 byte header + 5 byte string with null)
The bug was introduced in commit 15d2540e0d62 ("tools: ynl: check for overflow of constructed messages") when refactoring from stpcpy() to strlen(). The original code correctly included the null terminator:
end = stpcpy(ynl_attr_data(attr), str); attr->nla_len = NLA_HDRLEN + NLA_ALIGN(end - (char *)ynl_attr_data(attr));
Since stpcpy() returns a pointer past the null terminator, the length included it. The refactored version using strlen() omitted the +1.
The fix also removes NLA_ALIGN() from nla_len calculation, since nla_len should contain actual attribute length, not aligned length. Alignment is only for calculating next attribute position. This makes the code consistent with ynl_attr_put().
CTRL_ATTR_FAMILY_NAME uses NLA_NUL_STRING policy which requires null terminator. Kernel validates with memchr() and rejects if not found.
Fixes: 15d2540e0d62 ("tools: ynl: check for overflow of constructed messages") Signed-off-by: Petr Oros poros@redhat.com Tested-by: Ivan Vecera ivecera@redhat.com Reviewed-by: Ivan Vecera ivecera@redhat.com Link: https://lore.kernel.org/20251018151737.365485-3-zahari.doychev@linux.com Link: https://patch.msgid.link/20251024132438.351290-1-poros@redhat.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/net/ynl/lib/ynl-priv.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/net/ynl/lib/ynl-priv.h b/tools/net/ynl/lib/ynl-priv.h index 824777d7e05ea..fca519d7ec9a7 100644 --- a/tools/net/ynl/lib/ynl-priv.h +++ b/tools/net/ynl/lib/ynl-priv.h @@ -314,7 +314,7 @@ ynl_attr_put_str(struct nlmsghdr *nlh, unsigned int attr_type, const char *str) struct nlattr *attr; size_t len;
- len = strlen(str); + len = strlen(str) + 1; if (__ynl_attr_put_overflow(nlh, len)) return;
@@ -322,7 +322,7 @@ ynl_attr_put_str(struct nlmsghdr *nlh, unsigned int attr_type, const char *str) attr->nla_type = attr_type;
strcpy((char *)ynl_attr_data(attr), str); - attr->nla_len = NLA_HDRLEN + NLA_ALIGN(len); + attr->nla_len = NLA_HDRLEN + len;
nlh->nlmsg_len += NLMSG_ALIGN(attr->nla_len); }