CVE-2024-56593: wifi: brcmfmac: Fix oops due to NULL pointer dereference in brcmf_sdiod_sglist_rw()
In the Linux kernel, the following vulnerability has been resolved:
wifi: brcmfmac: Fix oops due to NULL pointer dereference in brcmfsdiodsglistrw()
This patch fixes a NULL pointer dereference bug in brcmfmac that occurs when a high 'sdsgentryalign' value applies (e.g. 512) and a lot of queued SKBs are sent from the pkt queue.
The problem is the number of entries in the pre-allocated sgtable, it is nents = max(rxglomsize, txglomsize) + max(rxglomsize, txglomsize) >> 4 + 1. Given the default [rt]xglomsize=32 it's actually 35 which is too small. Worst case, the pkt queue can end up with 64 SKBs. This occurs when a new SKB is added for each original SKB if tailroom isn't enough to hold tailpad. At least one sg entry is needed for each SKB. So, eventually the "skbqueuewalk loop" in brcmfsdiodsglistrw may run out of sg entries. This makes sgnext return NULL and this causes the oops.
The patch sets nents to max(rxglomsize, txglomsize) 2 to be able handle the worst-case. Btw. this requires only 64-35=29 16 (or 20 if CONFIGNEEDSGDMALENGTH) = 464 additional bytes of memory.
Other sources
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— Launchpad
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2024-56593?
CVE-2024-56593 is categorized as a moderate severity issue due to the potential for a NULL pointer dereference in the Linux kernel's brcmfmac component.
How do I fix CVE-2024-56593?
To fix CVE-2024-56593, you should upgrade your Linux kernel to a version that includes the patch addressing this vulnerability.
What affected versions are vulnerable to CVE-2024-56593?
CVE-2024-56593 affects Linux kernel versions prior to 5.4.287, between 5.5 and 5.10.231, between 5.11 and 5.15.174, between 5.16 and 6.1.120, between 6.2 and 6.6.66, and between 6.7 and 6.12.5.
What component of the Linux kernel is affected by CVE-2024-56593?
The vulnerability CVE-2024-56593 specifically affects the brcmfmac component of the Linux kernel.
When was CVE-2024-56593 disclosed?
CVE-2024-56593 was disclosed as part of a series of patches meant to address various issues in the Linux kernel.