| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Wed, 3 Apr 2024 19:31:07 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-cve-announce@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org> Subject: CVE-2024-26737: bpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel Description =========== In the Linux kernel, the following vulnerability has been resolved: bpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel The following race is possible between bpf_timer_cancel_and_free and bpf_timer_cancel. It will lead a UAF on the timer->timer. bpf_timer_cancel(); spin_lock(); t = timer->time; spin_unlock(); bpf_timer_cancel_and_free(); spin_lock(); t = timer->timer; timer->timer = NULL; spin_unlock(); hrtimer_cancel(&t->timer); kfree(t); /* UAF on t */ hrtimer_cancel(&t->timer); In bpf_timer_cancel_and_free, this patch frees the timer->timer after a rcu grace period. This requires a rcu_head addition to the "struct bpf_hrtimer". Another kfree(t) happens in bpf_timer_init, this does not need a kfree_rcu because it is still under the spin_lock and timer->timer has not been visible by others yet. In bpf_timer_cancel, rcu_read_lock() is added because this helper can be used in a non rcu critical section context (e.g. from a sleepable bpf prog). Other timer->timer usages in helpers.c have been audited, bpf_timer_cancel() is the only place where timer->timer is used outside of the spin_lock. Another solution considered is to mark a t->flag in bpf_timer_cancel and clear it after hrtimer_cancel() is done. In bpf_timer_cancel_and_free, it busy waits for the flag to be cleared before kfree(t). This patch goes with a straight forward solution and frees timer->timer after a rcu grace period. The Linux kernel CVE team has assigned CVE-2024-26737 to this issue. Affected and fixed versions =========================== Issue introduced in 5.15 with commit b00628b1c7d5 and fixed in 5.15.150 with commit 5268bb02107b Issue introduced in 5.15 with commit b00628b1c7d5 and fixed in 6.1.80 with commit addf5e297e6c Issue introduced in 5.15 with commit b00628b1c7d5 and fixed in 6.6.19 with commit 8327ed12e8eb Issue introduced in 5.15 with commit b00628b1c7d5 and fixed in 6.7.7 with commit 7d80a9e745fa Issue introduced in 5.15 with commit b00628b1c7d5 and fixed in 6.8 with commit 0281b919e175 Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2024-26737 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: kernel/bpf/helpers.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/5268bb02107b9eedfdcd51db75b407d10043368c https://git.kernel.org/stable/c/addf5e297e6cbf5341f9c07720693ca9ba0057b5 https://git.kernel.org/stable/c/8327ed12e8ebc5436bfaa1786c49988894f9c8a6 https://git.kernel.org/stable/c/7d80a9e745fa5b47da3bca001f186c02485c7c33 https://git.kernel.org/stable/c/0281b919e175bb9c3128bd3872ac2903e9436e3f
Powered by blists - more mailing lists