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authorAnmol Karn <anmol.karan123@gmail.com>2020-11-20 00:40:43 +0530
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-12-11 13:36:42 +0100
commitf404d59d8324bee8ddde8d7eedff9cd27f67a79c (patch)
tree130133581eb502a398897044b7ee9f5d47284f31
parenta3564ff7ca062fa164126bdd7c395a835714f054 (diff)
rose: Fix Null pointer dereference in rose_send_frame()
[ Upstream commit 3b3fd068c56e3fbea30090859216a368398e39bf ] rose_send_frame() dereferences `neigh->dev` when called from rose_transmit_clear_request(), and the first occurrence of the `neigh` is in rose_loopback_timer() as `rose_loopback_neigh`, and it is initialized in rose_add_loopback_neigh() as NULL. i.e when `rose_loopback_neigh` used in rose_loopback_timer() its `->dev` was still NULL and rose_loopback_timer() was calling rose_rx_call_request() without checking for NULL. - net/rose/rose_link.c This bug seems to get triggered in this line: rose_call = (ax25_address *)neigh->dev->dev_addr; Fix it by adding NULL checking for `rose_loopback_neigh->dev` in rose_loopback_timer(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Suggested-by: Jakub Kicinski <kuba@kernel.org> Reported-by: syzbot+a1c743815982d9496393@syzkaller.appspotmail.com Tested-by: syzbot+a1c743815982d9496393@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=9d2a7ca8c7f2e4b682c97578dfa3f236258300b3 Signed-off-by: Anmol Karn <anmol.karan123@gmail.com> Link: https://lore.kernel.org/r/20201119191043.28813-1-anmol.karan123@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/rose/rose_loopback.c17
1 files changed, 13 insertions, 4 deletions
diff --git a/net/rose/rose_loopback.c b/net/rose/rose_loopback.c
index 344456206b70..0f371e50d9c4 100644
--- a/net/rose/rose_loopback.c
+++ b/net/rose/rose_loopback.c
@@ -99,10 +99,19 @@ static void rose_loopback_timer(unsigned long param)
}
if (frametype == ROSE_CALL_REQUEST) {
- if ((dev = rose_dev_get(dest)) != NULL) {
- if (rose_rx_call_request(skb, dev, rose_loopback_neigh, lci_o) == 0)
- kfree_skb(skb);
- } else {
+ if (!rose_loopback_neigh->dev) {
+ kfree_skb(skb);
+ continue;
+ }
+
+ dev = rose_dev_get(dest);
+ if (!dev) {
+ kfree_skb(skb);
+ continue;
+ }
+
+ if (rose_rx_call_request(skb, dev, rose_loopback_neigh, lci_o) == 0) {
+ dev_put(dev);
kfree_skb(skb);
}
} else {