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Subject[PATCH] module: don't modify argument of module_kallsyms_lookup_name()
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If we pass a pointer to a const string of the form "module:symbol"
module_kallsyms_lookup_name() will try to split the string at the colon,
i.e., will try to modify r/o data. That will, in fact, fail on a kernel
with enabled CONFIG_DEBUG_RODATA.

Avoid modifying the string passed as argument and operate on a copy
instead in case we need to split the string.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
---
kernel/module.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index cab4bce..5ce0784 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3557,16 +3557,17 @@ static unsigned long mod_find_symname(struct module *mod, const char *name)
unsigned long module_kallsyms_lookup_name(const char *name)
{
struct module *mod;
- char *colon;
+ char *colon, *mod_name;
unsigned long ret = 0;

/* Don't lock: we're in enough trouble already. */
preempt_disable();
if ((colon = strchr(name, ':')) != NULL) {
- *colon = '\0';
- if ((mod = find_module(name)) != NULL)
+ mod_name = kstrndup(name, colon - name, GFP_ATOMIC);
+ if (mod_name && (mod = find_module(mod_name)) != NULL) {
ret = mod_find_symname(mod, colon+1);
- *colon = ':';
+ kfree(mod_name);
+ }
} else {
list_for_each_entry_rcu(mod, &modules, list) {
if (mod->state == MODULE_STATE_UNFORMED)
--
1.7.10.4


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