[PATCH iproute2 v2] libgenl: make genl_add_mcast_grp set errno on error
From: Florian Westphal <fw@strlen.de>
Date: 2021-05-10 12:41:14
Subsystem:
library code, the rest · Maintainers:
Andrew Morton, Linus Torvalds
genl_add_mcast_grp doesn't set errno in all cases.
On kernels that support mptcp but lack event support (all kernels <= 5.11)
MPTCP_PM_EV_GRP_NAME won't be found and ip will exit with
"can't subscribe to mptcp events: Success"
Set errno to a meaningful value (ENOENT) when the group name isn't found
and also cover other spots where it returns nonzero with errno unset.
Fixes: ff619e4fd370 ("mptcp: add support for event monitoring")
Signed-off-by: Florian Westphal <fw@strlen.de>
---
Change since v1: fix libgenl instead of setting errno in the caller.
lib/libgenl.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/lib/libgenl.c b/lib/libgenl.c
index 4c51d47af46b..8b22c06e7941 100644
--- a/lib/libgenl.c
+++ b/lib/libgenl.c@@ -84,6 +84,7 @@ static int genl_parse_grps(struct rtattr *attr, const char *name, unsigned int * } } + errno = ENOENT; return -1; }
@@ -108,17 +109,22 @@ int genl_add_mcast_grp(struct rtnl_handle *grth, __u16 fnum, const char *group) ghdr = NLMSG_DATA(answer); len = answer->nlmsg_len; - if (answer->nlmsg_type != GENL_ID_CTRL) + if (answer->nlmsg_type != GENL_ID_CTRL) { + errno = EINVAL; goto err_free; + } len -= NLMSG_LENGTH(GENL_HDRLEN); - if (len < 0) + if (len < 0) { + errno = EINVAL; goto err_free; + } attrs = (struct rtattr *) ((char *) ghdr + GENL_HDRLEN); parse_rtattr(tb, CTRL_ATTR_MAX, attrs, len); if (tb[CTRL_ATTR_MCAST_GROUPS] == NULL) { + errno = ENOENT; fprintf(stderr, "Missing mcast groups TLV\n"); goto err_free; }
--
2.26.3