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livepatch: add module locking around kallsyms calls 

The list of loaded modules is walked through in
module_kallsyms_on_each_symbol (called by kallsyms_on_each_symbol). The
module_mutex lock should be acquired to prevent potential corruptions
in the list.

This was uncovered with new lockdep asserts in module code introduced by
the commit 0be964be0d ("module: Sanitize RCU usage and locking") in
recent next- trees.

Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
Miroslav Benes 2015-06-01 17:48:37 +02:00 committed by Jiri Kosina
parent 9497d7380b
commit 9a1bd63cda
1 changed files with 13 additions and 5 deletions
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18
kernel/livepatch/core.c
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@ -179,7 +179,9 @@ static int klp_find_object_symbol(const char *objname, const char *name,
.count = 0
};
mutex_lock(&module_mutex);
kallsyms_on_each_symbol(klp_find_callback, &args);
mutex_unlock(&module_mutex);
if (args.count == 0)
pr_err("symbol '%s' not found in symbol table\n", name);
@ -219,13 +221,19 @@ static int klp_verify_vmlinux_symbol(const char *name, unsigned long addr)
.name = name,
.addr = addr,
};
int ret;
if (kallsyms_on_each_symbol(klp_verify_callback, &args))
return 0;
mutex_lock(&module_mutex);
ret = kallsyms_on_each_symbol(klp_verify_callback, &args);
mutex_unlock(&module_mutex);
pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n",
name, addr);
return -EINVAL;
if (!ret) {
pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n",
name, addr);
return -EINVAL;
}
return 0;
}
static int klp_find_verify_func_addr(struct klp_object *obj,