FAILED: patch "[PATCH] arm64: __show_regs: Only resolve kernel symbols when running" failed to apply to 4.15-stable tree

The patch below does not apply to the 4.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: Will Deacon <[email protected]>
Date: Mon, 19 Feb 2018 16:46:57 +0000
Subject: [PATCH] arm64: __show_regs: Only resolve kernel symbols when running
at EL1

__show_regs pretty prints PC and LR by attempting to map them to kernel function names to improve the utility of crash reports. Unfortunately, this mapping is applied even when the pt_regs corresponds to user mode, resulting in a KASLR oracle.

Avoid this issue by only looking up the function symbols when the register state indicates that we're actually running at EL1.

index ad8aeb098b31..c0da6efe5465 100644
@@ -220,8 +220,15 @@ void __show_regs(struct pt_regs *regs)
 
 	show_regs_print_info(KERN_DEFAULT);
 	print_pstate(regs);
-	printk("pc : %pS\n", (void *)regs->pc);
-	printk("lr : %pS\n", (void *)lr);
+
+	if (!user_mode(regs)) {
+		printk("pc : %pS\n", (void *)regs->pc);
+		printk("lr : %pS\n", (void *)lr);
+	} else {
+		printk("pc : %016llx\n", regs->pc);
+		printk("lr : %016llx\n", lr);
+	}
+
 	printk("sp : %016llx\n", sp);
 
 	i = top_reg;

Hi Greg,

Backport for 4.15 below. The fix isn't relevant to older kernels, since we don't attempt to resolve kernel symbols here prior to 4.15.

Cheers,

Will

--->8

From: Will Deacon <[email protected]>
Date: Mon, 19 Feb 2018 16:46:57 +0000
Subject: [PATCH] arm64: __show_regs: Only resolve kernel symbols when running
at EL1

__show_regs pretty prints PC and LR by attempting to map them to kernel function names to improve the utility of crash reports. Unfortunately, this mapping is applied even when the pt_regs corresponds to user mode, resulting in a KASLR oracle.

Avoid this issue by only looking up the function symbols when the register state indicates that we're actually running at EL1.

---
 arch/arm64/kernel/process.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

index 583fd8154695..d6ca5fccb229 100644
@@ -221,8 +221,15 @@ void __show_regs(struct pt_regs *regs)
 
 	show_regs_print_info(KERN_DEFAULT);
 	print_pstate(regs);
-	print_symbol("pc : %s\n", regs->pc);
-	print_symbol("lr : %s\n", lr);
+
+	if (!user_mode(regs)) {
+		print_symbol("pc : %s\n", regs->pc);
+		print_symbol("lr : %s\n", lr);
+	} else {
+		printk("pc : %016llx\n", regs->pc);
+		printk("lr : %016llx\n", lr);
+	}
+
 	printk("sp : %016llx\n", sp);
 
 	i = top_reg;

2.1.4

Now applied, thanks.

greg k-h