Hello!
[IPV4]: severe locking bug in fib_semantics.c
The patch is for net-2.6.19, but the bug is present in all the kernels
since yore.
Found in 2.4 by Yixin Pan <[EMAIL PROTECTED]>. Why do we need lockdep,
when sharp-sighted eyes are available? :-)
> 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 <[EMAIL PROTECTED]>
---
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 4ea6c68..5dfdad5 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)
{
- spin_lock(&fib_info_lock);
+ spin_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 *f
fi->fib_dead = 1;
fib_info_put(fi);
}
- spin_unlock(&fib_info_lock);
+ spin_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_h
unsigned int old_size = fib_hash_size;
unsigned int i, bytes;
- spin_lock(&fib_info_lock);
+ spin_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_h
}
fib_info_laddrhash = new_laddrhash;
- spin_unlock(&fib_info_lock);
+ spin_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);
- spin_lock(&fib_info_lock);
+ spin_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)
- spin_unlock(&fib_info_lock);
+ spin_unlock_bh(&fib_info_lock);
return fi;
err_inval:
-
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