The following commit has been merged into the perf/core branch of tip: Commit-ID: fa6192adc32f4fdfe5b74edd5b210e12afd6ecc0 Gitweb: https://git.kernel.org/tip/fa6192adc32f4fdfe5b74edd5b210e12afd6ecc0 Author: Jiri Olsa <jolsa@xxxxxxxxxx> AuthorDate: Wed, 12 Feb 2025 23:04:33 +01:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Thu, 06 Mar 2025 12:22:45 +01:00 uprobes/x86: Harden uretprobe syscall trampoline check Jann reported a possible issue when trampoline_check_ip returns address near the bottom of the address space that is allowed to call into the syscall if uretprobes are not set up: https://lore.kernel.org/bpf/202502081235.5A6F352985@keescook/T/#m9d416df341b8fbc11737dacbcd29f0054413cbbf Though the mmap minimum address restrictions will typically prevent creating mappings there, let's make sure uretprobe syscall checks for that. Fixes: ff474a78cef5 ("uprobe: Add uretprobe syscall to speed up return probe") Reported-by: Jann Horn <jannh@xxxxxxxxxx> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx> Reviewed-by: Kees Cook <kees@xxxxxxxxxx> Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> Acked-by: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Link: https://lore.kernel.org/r/20250212220433.3624297-1-jolsa@xxxxxxxxxx --- arch/x86/kernel/uprobes.c | 14 +++++++++----- include/linux/uprobes.h | 2 ++ kernel/events/uprobes.c | 2 +- 3 files changed, 12 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 5a952c5..9194695 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -357,19 +357,23 @@ void *arch_uprobe_trampoline(unsigned long *psize) return &insn; } -static unsigned long trampoline_check_ip(void) +static unsigned long trampoline_check_ip(unsigned long tramp) { - unsigned long tramp = uprobe_get_trampoline_vaddr(); - return tramp + (uretprobe_syscall_check - uretprobe_trampoline_entry); } SYSCALL_DEFINE0(uretprobe) { struct pt_regs *regs = task_pt_regs(current); - unsigned long err, ip, sp, r11_cx_ax[3]; + unsigned long err, ip, sp, r11_cx_ax[3], tramp; + + /* If there's no trampoline, we are called from wrong place. */ + tramp = uprobe_get_trampoline_vaddr(); + if (unlikely(tramp == UPROBE_NO_TRAMPOLINE_VADDR)) + goto sigill; - if (regs->ip != trampoline_check_ip()) + /* Make sure the ip matches the only allowed sys_uretprobe caller. */ + if (unlikely(regs->ip != trampoline_check_ip(tramp))) goto sigill; err = copy_from_user(r11_cx_ax, (void __user *)regs->sp, sizeof(r11_cx_ax)); diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index a40efdd..2e46b69 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -39,6 +39,8 @@ struct page; #define MAX_URETPROBE_DEPTH 64 +#define UPROBE_NO_TRAMPOLINE_VADDR (~0UL) + struct uprobe_consumer { /* * handler() can return UPROBE_HANDLER_REMOVE to signal the need to diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 921ad91..70c84b9 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -2169,8 +2169,8 @@ void uprobe_copy_process(struct task_struct *t, unsigned long flags) */ unsigned long uprobe_get_trampoline_vaddr(void) { + unsigned long trampoline_vaddr = UPROBE_NO_TRAMPOLINE_VADDR; struct xol_area *area; - unsigned long trampoline_vaddr = -1; /* Pairs with xol_add_vma() smp_store_release() */ area = READ_ONCE(current->mm->uprobes_state.xol_area); /* ^^^ */
