diff mbox series

[5.10,059/221] static_call: Fix the module key fixup

Message ID 20210329075631.160677004@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg KH March 29, 2021, 7:56 a.m. UTC 
From: Peter Zijlstra <peterz@infradead.org>

[ 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 <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lkml.kernel.org/r/20210225220351.GE4746@worktop.programming.kicks-ass.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/static_call.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
diff mbox series

Patch

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);