AI Score
Confidence
Low
EPSS
Percentile
10.3%
SSVC
Exploitation
none
Automatable
no
Technical Impact
partial
In the Linux kernel, the following vulnerability has been resolved:
bpf, sockmap: Prevent lock inversion deadlock in map delete elem
syzkaller started using corpuses where a BPF tracing program deletes
elements from a sockmap/sockhash map. Because BPF tracing programs can be
invoked from any interrupt context, locks taken during a map_delete_elem
operation must be hardirq-safe. Otherwise a deadlock due to lock inversion
is possible, as reported by lockdep:
CPU0 CPU1
---- ----
lock(&htab->buckets[i].lock);
local_irq_disable();
lock(&host->lock);
lock(&htab->buckets[i].lock);
<Interrupt>
lock(&host->lock);
Locks in sockmap are hardirq-unsafe by design. We expects elements to be
deleted from sockmap/sockhash only in task (normal) context with interrupts
enabled, or in softirq context.
Detect when map_delete_elem operation is invoked from a context which is
not hardirq-unsafe, that is interrupts are disabled, and bail out with an
error.
Note that map updates are not affected by this issue. BPF verifier does not
allow updating sockmap/sockhash from a BPF tracing program today.
git.kernel.org/stable/c/668b3074aa14829e2ac2759799537a93b60fef86
git.kernel.org/stable/c/6af057ccdd8e7619960aca1f0428339f213b31cd
git.kernel.org/stable/c/913c30f827e17d8cda1da6eeb990f350d36cb69b
git.kernel.org/stable/c/a44770fed86515eedb5a7c00b787f847ebb134a5
git.kernel.org/stable/c/d1e73fb19a4c872d7a399ad3c66e8ca30e0875ec
git.kernel.org/stable/c/dd54b48db0c822ae7b520bc80751f0a0a173ef75
git.kernel.org/stable/c/f7990498b05ac41f7d6a190dc0418ef1d21bf058
git.kernel.org/stable/c/ff91059932401894e6c86341915615c5eb0eca48