From: Andy Whitcroft Date: Thu, 13 Aug 2015 19:49:01 +0000 (+0100) Subject: ipv4: off-by-one in continuation handling in /proc/net/route X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=25b97c016b26039982daaa2c11d83979f93b71ab;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git ipv4: off-by-one in continuation handling in /proc/net/route 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 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. Fixes: 8be33e955cb9 ("fib_trie: Fib walk rcu should take a tnode and key instead of a trie and a leaf") BugLink: http://bugs.launchpad.net/bugs/1483440 Acked-by: Alexander Duyck Signed-off-by: Andy Whitcroft Signed-off-by: David S. Miller --- diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 37c4bb89a708..b0c6258ffb79 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;