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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.

Cc: <stable@vger.kernel.org>
Reported-by: NCSC Security <security@ncsc.gov.uk>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon 2018-02-19 16:46:57 +00:00
parent 1962682d2b
commit a06f818a70
1 changed files with 9 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
arch/arm64/kernel/process.c
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@ -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;