| Message ID | 1439461267-10627-1-git-send-email-apw@canonical.com |
|---|---|
| State | Superseded, archived |
| Delegated to: | David Miller |
| Headers | show |
On Thu, 2015-08-13 at 11:21 +0100, Andy Whitcroft wrote: > When generating /proc/net/route we emit a header followed by a line for > each route. When a short read is performed we will restart this process > based on the open file descriptor. When calculating the start point we > fail to take into account that the 0th entry is the header. This leads > us to skip the first entry when doing a continuation read. > > This can be easily seen with the comparison below: > > while read l; do echo "$l"; done </proc/net/route >A > cat /proc/net/route >B > diff -bu A B | grep '^[+-]' > > On my example machine I have approximatly 10KB of route output. There we > see the very first non-title element is lost in the while read case, > and an entry around the 8K mark in the cat case: > > +wlan0 00000000 02021EAC 0003 0 0 400 00000000 0 0 0 > -tun1 00C0AC0A 00000000 0001 0 0 950 00C0FFFF 0 0 0 > > Fix up the off-by-one when reaquiring position on continuation. > > BugLink: http://bugs.launchpad.net/bugs/1483440 > Signed-off-by: Andy Whitcroft <apw@canonical.com> > --- > net/ipv4/fib_trie.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > From code inspection I belive this was introduced by the Fixes > below, but I have not tested this to confirm. > > Fixes: 8be33e955cb9 ("ipv4: off-by-one in continuation handling in /proc/net/route") You probably meant Fixes: 8be33e955cb9 ("fib_trie: Fib walk rcu should take a tnode and key instead of a trie and a leaf") CC Alexander for review/comment -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 08/13/2015 08:10 AM, Eric Dumazet wrote: > On Thu, 2015-08-13 at 11:21 +0100, Andy Whitcroft wrote: >> When generating /proc/net/route we emit a header followed by a line for >> each route. When a short read is performed we will restart this process >> based on the open file descriptor. When calculating the start point we >> fail to take into account that the 0th entry is the header. This leads >> us to skip the first entry when doing a continuation read. >> >> This can be easily seen with the comparison below: >> >> while read l; do echo "$l"; done </proc/net/route >A >> cat /proc/net/route >B >> diff -bu A B | grep '^[+-]' >> >> On my example machine I have approximatly 10KB of route output. There we >> see the very first non-title element is lost in the while read case, >> and an entry around the 8K mark in the cat case: >> >> +wlan0 00000000 02021EAC 0003 0 0 400 00000000 0 0 0 >> -tun1 00C0AC0A 00000000 0001 0 0 950 00C0FFFF 0 0 0 >> >> Fix up the off-by-one when reaquiring position on continuation. >> >> BugLink: http://bugs.launchpad.net/bugs/1483440 >> Signed-off-by: Andy Whitcroft <apw@canonical.com> >> --- >> net/ipv4/fib_trie.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> From code inspection I belive this was introduced by the Fixes >> below, but I have not tested this to confirm. >> >> Fixes: 8be33e955cb9 ("ipv4: off-by-one in continuation handling in /proc/net/route") > You probably meant > > Fixes: 8be33e955cb9 ("fib_trie: Fib walk rcu should take a tnode and key instead of a trie and a leaf") > > CC Alexander for review/comment I agree the Fixes line needs to be updated. Other than that the fix looks good. Once you get the comment fixed feel free to add my acked-by. Also you might call out that this is needed for net, and 4.1 stable as well. Acked-by: Alexander Duyck <alexander.h.duyck@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 37c4bb8..b0c6258 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -2465,7 +2465,7 @@ static struct key_vector *fib_route_get_idx(struct fib_route_iter *iter, key = l->key + 1; iter->pos++; - if (pos-- <= 0) + if (--pos <= 0) break; l = NULL;
When generating /proc/net/route we emit a header followed by a line for each route. When a short read is performed we will restart this process based on the open file descriptor. When calculating the start point we fail to take into account that the 0th entry is the header. This leads us to skip the first entry when doing a continuation read. This can be easily seen with the comparison below: while read l; do echo "$l"; done </proc/net/route >A cat /proc/net/route >B diff -bu A B | grep '^[+-]' On my example machine I have approximatly 10KB of route output. There we see the very first non-title element is lost in the while read case, and an entry around the 8K mark in the cat case: +wlan0 00000000 02021EAC 0003 0 0 400 00000000 0 0 0 -tun1 00C0AC0A 00000000 0001 0 0 950 00C0FFFF 0 0 0 Fix up the off-by-one when reaquiring position on continuation. BugLink: http://bugs.launchpad.net/bugs/1483440 Signed-off-by: Andy Whitcroft <apw@canonical.com> --- net/ipv4/fib_trie.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) From code inspection I belive this was introduced by the Fixes below, but I have not tested this to confirm. Fixes: 8be33e955cb9 ("ipv4: off-by-one in continuation handling in /proc/net/route")