| Message ID | 20201119191043.28813-1-anmol.karan123@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [Linux-kernel-mentees,v5,net] rose: Fix Null pointer dereference in rose_send_frame() | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net |
| netdev/subject_prefix | success | Link |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | warning | WARNING: line length of 94 exceeds 80 columns |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
| netdev/stable | success | Stable not CCed |
On Fri, 20 Nov 2020 00:40:43 +0530 Anmol Karn wrote: > 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> Applied to net, thanks!
diff --git a/net/rose/rose_loopback.c b/net/rose/rose_loopback.c index 7b094275ea8b..11c45c8c6c16 100644 --- a/net/rose/rose_loopback.c +++ b/net/rose/rose_loopback.c @@ -96,10 +96,19 @@ static void rose_loopback_timer(struct timer_list *unused) } 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 {
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> --- Changes in v5: - Free `dev` in rose_rx_call_request() and add NULL check for `dev` before freeing it. (Suggested-by: Jakub Kicinski <kuba@kernel.org>) Changes in v4: - Free `dev`(on dev_hold()), when neigh->dev is NULL. (Suggested-by: Jakub Kicinski <kuba@kernel.org>) Changes in v3: - Corrected checkpatch warnings and errors (Suggested-by: Saeed Mahameed <saeed@kernel.org>) - Added "Fixes:" tag (Suggested-by: Saeed Mahameed <saeed@kernel.org>) Changes in v2: - Added NULL check in rose_loopback_timer() (Suggested-by: Greg KH <gregkh@linuxfoundation.org>) net/rose/rose_loopback.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) -- 2.29.2