From: Qiu-ji Chen chenqiuji666@gmail.com

stable inclusion from stable-v5.10.231 commit d7408a052aa1b4f6fb6f1c7a8877b84017a07ac9 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBEDOW CVE: CVE-2024-56700

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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commit ca59f9956d4519ab18ab2270be47c6b8c6ced091 upstream.

Atomicity violation occurs when the fmc_send_cmd() function is executed simultaneously with the modification of the fmdev->resp_skb value. Consider a scenario where, after passing the validity check within the function, a non-null fmdev->resp_skb variable is assigned a null value. This results in an invalid fmdev->resp_skb variable passing the validity check. As seen in the later part of the function, skb = fmdev->resp_skb; when the invalid fmdev->resp_skb passes the check, a null pointer dereference error may occur at line 478, evt_hdr = (void *)skb->data;

To address this issue, it is recommended to include the validity check of fmdev->resp_skb within the locked section of the function. This modification ensures that the value of fmdev->resp_skb does not change during the validation process, thereby maintaining its validity.

This possible bug is found by an experimental static analysis tool developed by our team. This tool analyzes the locking APIs to extract function pairs that can be concurrently executed, and then analyzes the instructions in the paired functions to identify possible concurrency bugs including data races and atomicity violations.

Fixes: e8454ff7b9a4 ("[media] drivers:media:radio: wl128x: FM Driver Common sources") Cc: stable@vger.kernel.org Signed-off-by: Qiu-ji Chen chenqiuji666@gmail.com Signed-off-by: Hans Verkuil hverkuil-cisco@xs4all.nl Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: dinglongwei dinglongwei1@huawei.com --- drivers/media/radio/wl128x/fmdrv_common.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/radio/wl128x/fmdrv_common.c b/drivers/media/radio/wl128x/fmdrv_common.c index 6142484d5cb4..d9287a935a9e 100644 --- a/drivers/media/radio/wl128x/fmdrv_common.c +++ b/drivers/media/radio/wl128x/fmdrv_common.c @@ -465,11 +465,12 @@ int fmc_send_cmd(struct fmdev *fmdev, u8 fm_op, u16 type, void *payload, jiffies_to_msecs(FM_DRV_TX_TIMEOUT) / 1000); return -ETIMEDOUT; } + spin_lock_irqsave(&fmdev->resp_skb_lock, flags); if (!fmdev->resp_skb) { + spin_unlock_irqrestore(&fmdev->resp_skb_lock, flags); fmerr("Response SKB is missing\n"); return -EFAULT; } - spin_lock_irqsave(&fmdev->resp_skb_lock, flags); skb = fmdev->resp_skb; fmdev->resp_skb = NULL; spin_unlock_irqrestore(&fmdev->resp_skb_lock, flags);