6.12-stable review patch. If anyone has any objections, please let me know.
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From: Jiri Olsa jolsa@kernel.org
commit fa6192adc32f4fdfe5b74edd5b210e12afd6ecc0 upstream.
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/#m9d416df341b...
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@google.com Signed-off-by: Jiri Olsa jolsa@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Reviewed-by: Oleg Nesterov oleg@redhat.com Reviewed-by: Kees Cook kees@kernel.org Acked-by: Andrii Nakryiko andrii@kernel.org Acked-by: Masami Hiramatsu (Google) mhiramat@kernel.org Acked-by: Alexei Starovoitov alexei.starovoitov@gmail.com Cc: Andy Lutomirski luto@kernel.org Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250212220433.3624297-1-jolsa@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/uprobes.c | 14 +++++++++----- include/linux/uprobes.h | 2 ++ kernel/events/uprobes.c | 2 +- 3 files changed, 12 insertions(+), 6 deletions(-)
--- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -357,19 +357,23 @@ void *arch_uprobe_trampoline(unsigned lo 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)); --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -28,6 +28,8 @@ 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 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1898,8 +1898,8 @@ void uprobe_copy_process(struct task_str */ 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); /* ^^^ */