From 0fefb5f3e5742cac36bcaea1be06c577e22fb6f7 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 25 Feb 2021 23:03:51 +0100 Subject: [PATCH] static_call: Fix the module key fixup [ Upstream commit 50bf8080a94d171e843fc013abec19d8ab9f50ae ] Provided the target address of a R_X86_64_PC32 relocation is aligned, the low two bits should be invariant between the relative and absolute value. Turns out the address is not aligned and things go sideways, ensure we transfer the bits in the absolute form when fixing up the key address. Fixes: 73f44fe19d35 ("static_call: Allow module use without exposing static_call_key") Reported-by: Steven Rostedt Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Tested-by: Steven Rostedt (VMware) Link: https://lkml.kernel.org/r/20210225220351.GE4746@worktop.programming.kicks-ass.net Signed-off-by: Sasha Levin --- kernel/static_call.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/static_call.c b/kernel/static_call.c index db64c2331a32..5d53c354fbe7 100644 --- a/kernel/static_call.c +++ b/kernel/static_call.c @@ -358,7 +358,8 @@ static int static_call_add_module(struct module *mod) struct static_call_site *site; for (site = start; site != stop; site++) { - unsigned long addr = (unsigned long)static_call_key(site); + unsigned long s_key = (long)site->key + (long)&site->key; + unsigned long addr = s_key & ~STATIC_CALL_SITE_FLAGS; unsigned long key; /* @@ -382,8 +383,8 @@ static int static_call_add_module(struct module *mod) return -EINVAL; } - site->key = (key - (long)&site->key) | - (site->key & STATIC_CALL_SITE_FLAGS); + key |= s_key & STATIC_CALL_SITE_FLAGS; + site->key = key - (long)&site->key; } return __static_call_init(mod, start, stop);