[BZ,#21812] getifaddrs() Don't return ifa entries with NULL names
Commit Message
Due to bug 21812, a lookup operation in map_newlink() turns out
into an insert because of holes in the interface part of the map.
This leads to incorrectly set the name of the interface to NULL when
the interface is not present for the address being processed (most
likely because the interface was added between the RTM_GETLINK and
RTM_GETADDR calls to the kernel).
This patch checks this condition and retries the whole operation.
Hopes are that next time the interface corresponding to the address
entry is present in the list and correct name is returned.
Signed-off-by: Daniel Alvarez <dalvarez@redhat.com>
---
sysdeps/unix/sysv/linux/ifaddrs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Comments
On 07/24/2017 10:56 PM, Daniel Alvarez wrote:
> Due to bug 21812, a lookup operation in map_newlink() turns out
> into an insert because of holes in the interface part of the map.
> This leads to incorrectly set the name of the interface to NULL when
> the interface is not present for the address being processed (most
> likely because the interface was added between the RTM_GETLINK and
> RTM_GETADDR calls to the kernel).
>
> This patch checks this condition and retries the whole operation.
> Hopes are that next time the interface corresponding to the address
> entry is present in the list and correct name is returned.
>
> Signed-off-by: Daniel Alvarez <dalvarez@redhat.com>
The downstream bug has a different patch:
<https://bugzilla.redhat.com/show_bug.cgi?id=1472832>
I think using NLM_F_DUMP_INTR to check the inconsistency is preferable
(if it actually works). glibc requires kernel 3.2 these days, so we can
assume that kernel support is present.
Thanks,
Florian
@@ -740,7 +740,7 @@ getifaddrs_internal (struct ifaddrs **ifap)
{
int idx = map_newlink (ifam->ifa_index - 1, ifas,
map_newlink_data, newlink);
- if (__glibc_unlikely (idx == -1))
+ if (__glibc_unlikely (idx == -1) || ifas[idx].ifa.ifa_name == NULL)
goto try_again;
ifas[ifa_index].ifa.ifa_name = ifas[idx].ifa.ifa_name;
}