CVE - CVE-2024-36937

CVE-ID
CVE-2024-36937	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
In the Linux kernel, the following vulnerability has been resolved: xdp: use flags field to disambiguate broadcast redirect When redirecting a packet using XDP, the bpf_redirect_map() helper will set up the redirect destination information in struct bpf_redirect_info (using the __bpf_xdp_redirect_map() helper function), and the xdp_do_redirect() function will read this information after the XDP program returns and pass the frame on to the right redirect destination. When using the BPF_F_BROADCAST flag to do multicast redirect to a whole map, __bpf_xdp_redirect_map() sets the 'map' pointer in struct bpf_redirect_info to point to the destination map to be broadcast. And xdp_do_redirect() reacts to the value of this map pointer to decide whether it's dealing with a broadcast or a single-value redirect. However, if the destination map is being destroyed before xdp_do_redirect() is called, the map pointer will be cleared out (by bpf_clear_redirect_map()) without waiting for any XDP programs to stop running. This causes xdp_do_redirect() to think that the redirect was to a single target, but the target pointer is also NULL (since broadcast redirects don't have a single target), so this causes a crash when a NULL pointer is passed to dev_map_enqueue(). To fix this, change xdp_do_redirect() to react directly to the presence of the BPF_F_BROADCAST flag in the 'flags' value in struct bpf_redirect_info to disambiguate between a single-target and a broadcast redirect. And only read the 'map' pointer if the broadcast flag is set, aborting if that has been cleared out in the meantime. This prevents the crash, while keeping the atomic (cmpxchg-based) clearing of the map pointer itself, and without adding any more checks in the non-broadcast fast path.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/12481f30128fbebc2eeb55eb2d56390fdfa30c5e URL:https://git.kernel.org/stable/c/12481f30128fbebc2eeb55eb2d56390fdfa30c5e MISC:https://git.kernel.org/stable/c/272bfb019f3cc018f654b992115774e77b4f3ffc URL:https://git.kernel.org/stable/c/272bfb019f3cc018f654b992115774e77b4f3ffc MISC:https://git.kernel.org/stable/c/5bcf0dcbf9066348058b88a510c57f70f384c92c URL:https://git.kernel.org/stable/c/5bcf0dcbf9066348058b88a510c57f70f384c92c MISC:https://git.kernel.org/stable/c/6fd81f9d333e7b3532036577b1beb74ba1323553 URL:https://git.kernel.org/stable/c/6fd81f9d333e7b3532036577b1beb74ba1323553 MISC:https://git.kernel.org/stable/c/e22e25820fa04ea5eaac4ef7ee200e9923f466a4 URL:https://git.kernel.org/stable/c/e22e25820fa04ea5eaac4ef7ee200e9923f466a4
Assigning CNA
kernel.org
Date Record Created
20240530	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20240530)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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