Re: [PATCH] hsr: fix NULL pointer dereference in skb_clone with hw tag insertion
From: Greg KH <gregkh@linuxfoundation.org>
Date: 2025-11-27 15:20:26
Also in:
linux-kernel-mentees, lkml
On Wed, Nov 26, 2025 at 02:31:58AM +0530, ssrane_b23@ee.vjti.ac.in wrote:
quoted hunk ↗ jump to hunk
From: Shaurya Rane <redacted> When hardware HSR tag insertion is enabled (NETIF_F_HW_HSR_TAG_INS) and frame->skb_std is NULL, both hsr_create_tagged_frame() and prp_create_tagged_frame() will call skb_clone() with a NULL skb pointer, causing a kernel crash. Fix this by adding NULL checks for frame->skb_std before calling skb_clone() in the functions. Reported-by: syzbot+2fa344348a579b779e05@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=2fa344348a579b779e05 Fixes: f266a683a480 ("net/hsr: Better frame dispatch") Signed-off-by: Shaurya Rane <redacted> --- net/hsr/hsr_forward.c | 7 +++++++ 1 file changed, 7 insertions(+)diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c index 339f0d220212..4c1a311b900f 100644 --- a/net/hsr/hsr_forward.c +++ b/net/hsr/hsr_forward.c@@ -211,6 +211,9 @@ struct sk_buff *prp_get_untagged_frame(struct hsr_frame_info *frame, __FILE__, __LINE__, port->dev->name); return NULL; } + + if (!frame->skb_std) + return NULL; } return skb_clone(frame->skb_std, GFP_ATOMIC);@@ -341,6 +344,8 @@ struct sk_buff *hsr_create_tagged_frame(struct hsr_frame_info *frame, hsr_set_path_id(frame, hsr_ethhdr, port); return skb_clone(frame->skb_hsr, GFP_ATOMIC); } else if (port->dev->features & NETIF_F_HW_HSR_TAG_INS) { + if (!frame->skb_std) + return NULL; return skb_clone(frame->skb_std, GFP_ATOMIC); }@@ -385,6 +390,8 @@ struct sk_buff *prp_create_tagged_frame(struct hsr_frame_info *frame, } return skb_clone(frame->skb_prp, GFP_ATOMIC); } else if (port->dev->features & NETIF_F_HW_HSR_TAG_INS) { + if (!frame->skb_std) + return NULL; return skb_clone(frame->skb_std, GFP_ATOMIC); }-- 2.34.1
Hi, This is the friendly patch-bot of Greg Kroah-Hartman. You have sent him a patch that has triggered this response. He used to manually respond to these common problems, but in order to save his sanity (he kept writing the same thing over and over, yet to different people), I was created. Hopefully you will not take offence and will fix the problem in your patch and resubmit it so that it can be accepted into the Linux kernel tree. You are receiving this message because of the following common error(s) as indicated below: - You have marked a patch with a "Fixes:" tag for a commit that is in an older released kernel, yet you do not have a cc: stable line in the signed-off-by area at all, which means that the patch will not be applied to any older kernel releases. To properly fix this, please follow the documented rules in the Documentation/process/stable-kernel-rules.rst file for how to resolve this. If you wish to discuss this problem further, or you have questions about how to resolve this issue, please feel free to respond to this email and Greg will reply once he has dug out from the pending patches received from other developers. thanks, greg k-h's patch email bot