| Message ID | 20210421174007.2954194-1-bjorn.andersson@linaro.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 47a017f33943278570c072bc71681809b2567b3a |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: qrtr: Avoid potential use after free in MHI send | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Guessed tree name to be net-next |
| netdev/subject_prefix | warning | Target tree name not specified in the subject |
| netdev/cc_maintainers | success | CCed 6 of 6 maintainers |
| 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 | success | total: 0 errors, 0 warnings, 0 checks, 23 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
Hello: This patch was applied to netdev/net.git (refs/heads/master): On Wed, 21 Apr 2021 10:40:07 -0700 you wrote: > It is possible that the MHI ul_callback will be invoked immediately > following the queueing of the skb for transmission, leading to the > callback decrementing the refcount of the associated sk and freeing the > skb. > > As such the dereference of skb and the increment of the sk refcount must > happen before the skb is queued, to avoid the skb to be used after free > and potentially the sk to drop its last refcount.. > > [...] Here is the summary with links: - net: qrtr: Avoid potential use after free in MHI send https://git.kernel.org/netdev/net/c/47a017f33943 You are awesome, thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/patchwork/pwbot.html
On Wed, Apr 21, 2021 at 10:40:07AM -0700, Bjorn Andersson wrote: > It is possible that the MHI ul_callback will be invoked immediately > following the queueing of the skb for transmission, leading to the > callback decrementing the refcount of the associated sk and freeing the > skb. > > As such the dereference of skb and the increment of the sk refcount must > happen before the skb is queued, to avoid the skb to be used after free > and potentially the sk to drop its last refcount.. > > Fixes: 6e728f321393 ("net: qrtr: Add MHI transport layer") > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> Thanks, Mani > --- > net/qrtr/mhi.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c > index 2bf2b1943e61..fa611678af05 100644 > --- a/net/qrtr/mhi.c > +++ b/net/qrtr/mhi.c > @@ -50,6 +50,9 @@ static int qcom_mhi_qrtr_send(struct qrtr_endpoint *ep, struct sk_buff *skb) > struct qrtr_mhi_dev *qdev = container_of(ep, struct qrtr_mhi_dev, ep); > int rc; > > + if (skb->sk) > + sock_hold(skb->sk); > + > rc = skb_linearize(skb); > if (rc) > goto free_skb; > @@ -59,12 +62,11 @@ static int qcom_mhi_qrtr_send(struct qrtr_endpoint *ep, struct sk_buff *skb) > if (rc) > goto free_skb; > > - if (skb->sk) > - sock_hold(skb->sk); > - > return rc; > > free_skb: > + if (skb->sk) > + sock_put(skb->sk); > kfree_skb(skb); > > return rc; > -- > 2.29.2 >
diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c index 2bf2b1943e61..fa611678af05 100644 --- a/net/qrtr/mhi.c +++ b/net/qrtr/mhi.c @@ -50,6 +50,9 @@ static int qcom_mhi_qrtr_send(struct qrtr_endpoint *ep, struct sk_buff *skb) struct qrtr_mhi_dev *qdev = container_of(ep, struct qrtr_mhi_dev, ep); int rc; + if (skb->sk) + sock_hold(skb->sk); + rc = skb_linearize(skb); if (rc) goto free_skb; @@ -59,12 +62,11 @@ static int qcom_mhi_qrtr_send(struct qrtr_endpoint *ep, struct sk_buff *skb) if (rc) goto free_skb; - if (skb->sk) - sock_hold(skb->sk); - return rc; free_skb: + if (skb->sk) + sock_put(skb->sk); kfree_skb(skb); return rc;
It is possible that the MHI ul_callback will be invoked immediately following the queueing of the skb for transmission, leading to the callback decrementing the refcount of the associated sk and freeing the skb. As such the dereference of skb and the increment of the sk refcount must happen before the skb is queued, to avoid the skb to be used after free and potentially the sk to drop its last refcount.. Fixes: 6e728f321393 ("net: qrtr: Add MHI transport layer") Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> --- net/qrtr/mhi.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)