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| author |   Peter Zijlstra <peterz@infradead.org> | 2015-02-28 22:24:48 +0100 |
|---|---|---|
| committer |   Jiri Kosina <jkosina@suse.cz> | 2015-03-03 00:22:55 +0100 |
| commit | c064a0de1bfb07c34a3798822c7e1636eea866e8 (patch) | |
| tree | d91896f9a004e5e36809262a85791d6aec85a89e /kernel/livepatch/core.c | |
| parent | livepatch: RCU protect struct klp_func all the time when used in klp_ftrace_handler() (diff) | |
| download | linux-dev-c064a0de1bfb07c34a3798822c7e1636eea866e8.tar.xz linux-dev-c064a0de1bfb07c34a3798822c7e1636eea866e8.zip | |
livepatch: fix RCU usage in klp_find_external_symbol()
While one must hold RCU-sched (aka. preempt_disable) for find_symbol()
one must equally hold it over the use of the object returned.
The moment you release the RCU-sched read lock, the object can be dead
and gone.
[jkosina@suse.cz: change subject line to be aligned with other patches]
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.cz>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to '')
| -rw-r--r-- | kernel/livepatch/core.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index 782172f073c5..01ca08804f51 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -248,11 +248,12 @@ static int klp_find_external_symbol(struct module *pmod, const char *name, /* first, check if it's an exported symbol */ preempt_disable(); sym = find_symbol(name, NULL, NULL, true, true); - preempt_enable(); if (sym) { *addr = sym->value; + preempt_enable(); return 0; } + preempt_enable(); /* otherwise check if it's in another .o within the patch module */ return klp_find_object_symbol(pmod->name, name, addr); |