[PATCH 3.4 010/125] net: fix a race in dst_release()

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



From: Eric Dumazet <edumazet@xxxxxxxxxx>

3.4.113-rc1 review patch.  If anyone has any objections, please let me know.

------------------


commit d69bbf88c8d0b367cf3e3a052f6daadf630ee566 upstream.

Only cpu seeing dst refcount going to 0 can safely
dereference dst->flags.

Otherwise an other cpu might already have freed the dst.

Fixes: 27b75c95f10d ("net: avoid RCU for NOCACHE dst")
Reported-by: Greg Thelen <gthelen@xxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
 net/core/dst.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/dst.c b/net/core/dst.c
index 43d94ce..54ba1eb 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -272,7 +272,7 @@ void dst_release(struct dst_entry *dst)
 
 		newrefcnt = atomic_dec_return(&dst->__refcnt);
 		WARN_ON(newrefcnt < 0);
-		if (unlikely(dst->flags & DST_NOCACHE) && !newrefcnt) {
+		if (!newrefcnt && unlikely(dst->flags & DST_NOCACHE)) {
 			dst = dst_destroy(dst);
 			if (dst)
 				__dst_free(dst);
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]