From: David Windsor Date: Tue, 30 Jun 2026 00:13:33 +0000 (-0400) Subject: x86/uprobes: Keep shadow stack in sync for emulated CALLs X-Git-Tag: v7.2-rc2~2^2~2 X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=abf08854d224085e2ebb3ba660e7995909f47d6a;p=thirdparty%2Flinux.git x86/uprobes: Keep shadow stack in sync for emulated CALLs Uprobe CALL emulation updates the normal user stack, but not the CET user shadow stack. The subsequent RET then sees a stale shadow stack entry and raises #CP. Update the relative CALL emulation and XOL CALL fixup paths to keep the shadow stack in sync. Fixes: 488af8ea7131 ("x86/shstk: Wire in shadow stack interface") Signed-off-by: David Windsor Signed-off-by: Peter Zijlstra (Intel) Acked-by: Oleg Nesterov Acked-by: Jiri Olsa Tested-by: Jiri Olsa Link: https://patch.msgid.link/8b5b1c7407b98f31664ad7b6a6faf20d2d4a6cad.1782777969.git.dwindsor@gmail.com --- diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index ebb1baf1eb1d..d74bb54543b6 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -1246,9 +1246,15 @@ static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs long correction = utask->vaddr - utask->xol_vaddr; regs->ip += correction; } else if (auprobe->defparam.fixups & UPROBE_FIX_CALL) { + unsigned long retaddr = utask->vaddr + auprobe->defparam.ilen; + int err; + regs->sp += sizeof_long(regs); /* Pop incorrect return address */ - if (emulate_push_stack(regs, utask->vaddr + auprobe->defparam.ilen)) + if (emulate_push_stack(regs, retaddr)) return -ERESTART; + err = shstk_update_last_frame(retaddr); + if (err) + return err; } /* popf; tell the caller to not touch TF */ if (auprobe->defparam.fixups & UPROBE_FIX_SETF) @@ -1338,6 +1344,10 @@ static bool branch_emulate_op(struct arch_uprobe *auprobe, struct pt_regs *regs) */ if (emulate_push_stack(regs, new_ip)) return false; + if (shstk_push(new_ip) == -EFAULT) { + regs->sp += sizeof_long(regs); + return false; + } } else if (!check_jmp_cond(auprobe, regs)) { offs = 0; }