* [PATCH iproute2 v3] libgenl: make genl_add_mcast_grp set errno on error
@ 2021-05-17 5:10 Florian Westphal
2021-05-17 14:44 ` David Ahern
0 siblings, 1 reply; 2+ messages in thread
From: Florian Westphal @ 2021-05-17 5:10 UTC (permalink / raw)
To: netdev; +Cc: dsahern, Florian Westphal
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 v2: include errno.h
Change since v1: fix libgenl instead of setting errno in the caller.
lib/libgenl.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/lib/libgenl.c b/lib/libgenl.c
index 4c51d47af46b..fca07f9fe768 100644
--- a/lib/libgenl.c
+++ b/lib/libgenl.c
@@ -3,6 +3,7 @@
* libgenl.c GENL library
*/
+#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
@@ -84,6 +85,7 @@ static int genl_parse_grps(struct rtattr *attr, const char *name, unsigned int *
}
}
+ errno = ENOENT;
return -1;
}
@@ -108,17 +110,22 @@ 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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH iproute2 v3] libgenl: make genl_add_mcast_grp set errno on error
2021-05-17 5:10 [PATCH iproute2 v3] libgenl: make genl_add_mcast_grp set errno on error Florian Westphal
@ 2021-05-17 14:44 ` David Ahern
0 siblings, 0 replies; 2+ messages in thread
From: David Ahern @ 2021-05-17 14:44 UTC (permalink / raw)
To: Florian Westphal, netdev
On 5/16/21 11:10 PM, Florian Westphal wrote:
> 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 v2: include errno.h
> Change since v1: fix libgenl instead of setting errno in the caller.
> lib/libgenl.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
Reviewed-by: David Ahern <dsahern@kernel.org>
It is assigned to Stephen for main branch.
^ permalink raw reply [flat|nested] 2+ messages in thread
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