From: Stephen Brennan <stephen.s.brennan@oracle.com> mainline inclusion from mainline-v6.10-rc1 commit 1a7d0890dd4a502a202aaec792a6c04e6e049547 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/14968 CVE: CVE-2026-43409 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- If an error happens in ftrace, ftrace_kill() will prevent disarming kprobes. Eventually, the ftrace_ops associated with the kprobes will be freed, yet the kprobes will still be active, and when triggered, they will use the freed memory, likely resulting in a page fault and panic. This behavior can be reproduced quite easily, by creating a kprobe and then triggering a ftrace_kill(). For simplicity, we can simulate an ftrace error with a kernel module like [1]: [1]: https://github.com/brenns10/kernel_stuff/tree/master/ftrace_killer sudo perf probe --add commit_creds sudo perf trace -e probe:commit_creds # In another terminal make sudo insmod ftrace_killer.ko # calls ftrace_kill(), simulating bug # Back to perf terminal # ctrl-c sudo perf probe --del commit_creds After a short period, a page fault and panic would occur as the kprobe continues to execute and uses the freed ftrace_ops. While ftrace_kill() is supposed to be used only in extreme circumstances, it is invoked in FTRACE_WARN_ON() and so there are many places where an unexpected bug could be triggered, yet the system may continue operating, possibly without the administrator noticing. If ftrace_kill() does not panic the system, then we should do everything we can to continue operating, rather than leave a ticking time bomb. Link: https://lore.kernel.org/all/20240501162956.229427-1-stephen.s.brennan@oracle... Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Acked-by: Guo Ren <guoren@kernel.org> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Conflicts: arch/csky/kernel/probes/ftrace.c arch/loongarch/kernel/ftrace_dyn.c arch/parisc/kernel/ftrace.c arch/powerpc/kernel/kprobes-ftrace.c arch/riscv/kernel/probes/ftrace.c arch/s390/kernel/ftrace.c arch/x86/kernel/kprobes/ftrace.c include/linux/kprobes.h kernel/kprobes.c kernel/trace/ftrace.c [Context conflict] Signed-off-by: Tengda Wu <wutengda@huaweicloud.com> --- arch/csky/kernel/probes/ftrace.c | 3 +++ arch/parisc/kernel/ftrace.c | 3 +++ arch/powerpc/kernel/kprobes-ftrace.c | 3 +++ arch/s390/kernel/ftrace.c | 3 +++ arch/sw_64/kernel/kprobes/kprobes-ftrace.c | 3 +++ arch/x86/kernel/kprobes/ftrace.c | 3 +++ include/linux/kprobes.h | 8 ++++++++ kernel/kprobes.c | 6 ++++++ kernel/trace/ftrace.c | 1 + 9 files changed, 33 insertions(+) diff --git a/arch/csky/kernel/probes/ftrace.c b/arch/csky/kernel/probes/ftrace.c index 5264763d05be..98fc13eb2d4d 100644 --- a/arch/csky/kernel/probes/ftrace.c +++ b/arch/csky/kernel/probes/ftrace.c @@ -17,6 +17,9 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, struct kprobe *p; struct kprobe_ctlblk *kcb; + if (unlikely(kprobe_ftrace_disabled)) + return; + /* Preempt is disabled by ftrace */ p = get_kprobe((kprobe_opcode_t *)ip); if (!p) { diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c index 63e3ecb9da81..fb97172f7409 100644 --- a/arch/parisc/kernel/ftrace.c +++ b/arch/parisc/kernel/ftrace.c @@ -209,6 +209,9 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, struct kprobe_ctlblk *kcb; struct kprobe *p = get_kprobe((kprobe_opcode_t *)ip); + if (unlikely(kprobe_ftrace_disabled)) + return; + if (unlikely(!p) || kprobe_disabled(p)) return; diff --git a/arch/powerpc/kernel/kprobes-ftrace.c b/arch/powerpc/kernel/kprobes-ftrace.c index 972cb28174b2..605502f108b7 100644 --- a/arch/powerpc/kernel/kprobes-ftrace.c +++ b/arch/powerpc/kernel/kprobes-ftrace.c @@ -19,6 +19,9 @@ void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip, struct kprobe *p; struct kprobe_ctlblk *kcb; + if (unlikely(kprobe_ftrace_disabled)) + return; + p = get_kprobe((kprobe_opcode_t *)nip); if (unlikely(!p) || kprobe_disabled(p)) return; diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c index 923ecccae306..e4f0390833ac 100644 --- a/arch/s390/kernel/ftrace.c +++ b/arch/s390/kernel/ftrace.c @@ -205,6 +205,9 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, struct kprobe_ctlblk *kcb; struct kprobe *p = get_kprobe((kprobe_opcode_t *)ip); + if (unlikely(kprobe_ftrace_disabled)) + return; + if (unlikely(!p) || kprobe_disabled(p)) return; diff --git a/arch/sw_64/kernel/kprobes/kprobes-ftrace.c b/arch/sw_64/kernel/kprobes/kprobes-ftrace.c index 85a327a047a6..da8676b56d2c 100644 --- a/arch/sw_64/kernel/kprobes/kprobes-ftrace.c +++ b/arch/sw_64/kernel/kprobes/kprobes-ftrace.c @@ -16,6 +16,9 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, struct kprobe *p; struct kprobe_ctlblk *kcb; + if (unlikely(kprobe_ftrace_disabled)) + return; + p = get_kprobe((kprobe_opcode_t *)ip); if (unlikely(!p) || kprobe_disabled(p)) return; diff --git a/arch/x86/kernel/kprobes/ftrace.c b/arch/x86/kernel/kprobes/ftrace.c index 681a4b36e9bb..fc52bda72470 100644 --- a/arch/x86/kernel/kprobes/ftrace.c +++ b/arch/x86/kernel/kprobes/ftrace.c @@ -19,6 +19,9 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, struct kprobe *p; struct kprobe_ctlblk *kcb; + if (unlikely(kprobe_ftrace_disabled)) + return; + /* Preempt is disabled by ftrace */ p = get_kprobe((kprobe_opcode_t *)ip); if (unlikely(!p) || kprobe_disabled(p)) diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 28a6e871dac6..7ea60b3ba4d5 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -367,6 +367,11 @@ static inline void wait_for_kprobe_optimizer(void) { } extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *ops, struct pt_regs *regs); extern int arch_prepare_kprobe_ftrace(struct kprobe *p); +/* Set when ftrace has been killed: kprobes on ftrace must be disabled for safety */ +extern bool kprobe_ftrace_disabled __read_mostly; +extern void kprobe_ftrace_kill(void); +#else +static inline void kprobe_ftrace_kill(void) {} #endif int arch_check_ftrace_location(struct kprobe *p); @@ -471,6 +476,9 @@ static inline void kprobe_flush_task(struct task_struct *tk) static inline void kprobe_free_init_mem(void) { } +static inline void kprobe_ftrace_kill(void) +{ +} static inline int disable_kprobe(struct kprobe *kp) { return -ENOSYS; diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 5d64d97975ba..8f8679f9c012 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1030,6 +1030,7 @@ static struct ftrace_ops kprobe_ipmodify_ops __read_mostly = { static int kprobe_ipmodify_enabled; static int kprobe_ftrace_enabled; +bool kprobe_ftrace_disabled; /* Must ensure p->addr is really on ftrace */ static int prepare_kprobe(struct kprobe *p) @@ -1110,6 +1111,11 @@ static int disarm_kprobe_ftrace(struct kprobe *p) ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops, ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled); } + +void kprobe_ftrace_kill(void) +{ + kprobe_ftrace_disabled = true; +} #else /* !CONFIG_KPROBES_ON_FTRACE */ static inline int prepare_kprobe(struct kprobe *p) { diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 4b9a28a88de1..97a9dc142b57 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -7615,6 +7615,7 @@ void ftrace_kill(void) ftrace_disabled = 1; ftrace_enabled = 0; ftrace_trace_function = ftrace_stub; + kprobe_ftrace_kill(); } /** -- 2.34.1