From: Alexey Kuznetsov Date: Thu, 17 Aug 2006 23:44:46 +0000 (-0700) Subject: [IPV4]: severe locking bug in fib_semantics.c X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=6e8fcbf64024f9056ba122abbb66554aa76bae5d;p=linux-beck.git [IPV4]: severe locking bug in fib_semantics.c Found in 2.4 by Yixin Pan . > When I read fib_semantics.c of Linux-2.4.32, write_lock(&fib_info_lock) = > is used in fib_release_info() instead of write_lock_bh(&fib_info_lock). = > Is the following case possible: a BH interrupts fib_release_info() while = > holding the write lock, and calls ip_check_fib_default() which calls = > read_lock(&fib_info_lock), and spin forever. Signed-off-by: Alexey Kuznetsov Signed-off-by: David S. Miller --- diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c index 9be53a8e72c3..51738000f3dc 100644 --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -159,7 +159,7 @@ void free_fib_info(struct fib_info *fi) void fib_release_info(struct fib_info *fi) { - write_lock(&fib_info_lock); + write_lock_bh(&fib_info_lock); if (fi && --fi->fib_treeref == 0) { hlist_del(&fi->fib_hash); if (fi->fib_prefsrc) @@ -172,7 +172,7 @@ void fib_release_info(struct fib_info *fi) fi->fib_dead = 1; fib_info_put(fi); } - write_unlock(&fib_info_lock); + write_unlock_bh(&fib_info_lock); } static __inline__ int nh_comp(const struct fib_info *fi, const struct fib_info *ofi) @@ -598,7 +598,7 @@ static void fib_hash_move(struct hlist_head *new_info_hash, unsigned int old_size = fib_hash_size; unsigned int i, bytes; - write_lock(&fib_info_lock); + write_lock_bh(&fib_info_lock); old_info_hash = fib_info_hash; old_laddrhash = fib_info_laddrhash; fib_hash_size = new_size; @@ -639,7 +639,7 @@ static void fib_hash_move(struct hlist_head *new_info_hash, } fib_info_laddrhash = new_laddrhash; - write_unlock(&fib_info_lock); + write_unlock_bh(&fib_info_lock); bytes = old_size * sizeof(struct hlist_head *); fib_hash_free(old_info_hash, bytes); @@ -820,7 +820,7 @@ link_it: fi->fib_treeref++; atomic_inc(&fi->fib_clntref); - write_lock(&fib_info_lock); + write_lock_bh(&fib_info_lock); hlist_add_head(&fi->fib_hash, &fib_info_hash[fib_info_hashfn(fi)]); if (fi->fib_prefsrc) { @@ -839,7 +839,7 @@ link_it: head = &fib_info_devhash[hash]; hlist_add_head(&nh->nh_hash, head); } endfor_nexthops(fi) - write_unlock(&fib_info_lock); + write_unlock_bh(&fib_info_lock); return fi; err_inval: