Linux · Linux Kernel · CVE-2024-56700
**Name of the Vulnerable Software and Affected Versions**
Linux kernel (affected versions not specified)
**Description**
The issue is related to an atomicity violation in the `fmc send cmd()` function. This occurs when the function is executed simultaneously with the modification of the `fmdev->resp skb` value. If the `fmdev->resp skb` variable is assigned a null value after passing the validity check, it may result in a null pointer dereference error. The error can occur at the line where `evt hdr = (void *)skb->data;` is executed, because `skb = fmdev->resp skb;` may be invalid. To address this issue, it is recommended to include the validity check of `fmdev->resp skb` within the locked section of the function to maintain its validity.
**Recommendations**
To resolve the issue, include the validity check of `fmdev->resp skb` within the locked section of the `fmc send cmd()` function. This modification ensures that the value of `fmdev->resp skb` does not change during the validation process, thereby maintaining its validity. As a temporary workaround, consider adding locks to prevent concurrent execution of the `fmc send cmd()` function with the modification of the `fmdev->resp skb` value.