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authorAlexey Dobriyan <adobriyan@sw.ru>2007-05-08 00:28:43 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-08 11:15:08 -0700
commit9d65cb4a1718a072898c7a57a3bc61b2dc4bcd4d (patch)
tree9e3fd1c9e61e8ed16959d115a9a3f6f7eb0bbf21
parentffb45122766db220d0bf3d01848d575fbbcb6430 (diff)
Fix race between cat /proc/*/wchan and rmmod et al
kallsyms_lookup() can go iterating over modules list unprotected which is OK for emergency situations (oops), but not OK for regular stuff like /proc/*/wchan. Introduce lookup_symbol_name()/lookup_module_symbol_name() which copy symbol name into caller-supplied buffer or return -ERANGE. All copying is done with module_mutex held, so... Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/proc/base.c11
-rw-r--r--include/linux/kallsyms.h7
-rw-r--r--include/linux/module.h6
-rw-r--r--kernel/kallsyms.c17
-rw-r--r--kernel/module.c23
-rw-r--r--kernel/time/timer_list.c11
-rw-r--r--kernel/time/timer_stats.c10
7 files changed, 66 insertions, 19 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 3b4fe21c7e94..0c2052c79243 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -278,16 +278,15 @@ static int proc_pid_auxv(struct task_struct *task, char *buffer)
*/
static int proc_pid_wchan(struct task_struct *task, char *buffer)
{
- const char *sym_name;
unsigned long wchan;
- char namebuf[KSYM_NAME_LEN+1];
+ char symname[KSYM_NAME_LEN+1];
wchan = get_wchan(task);
- sym_name = kallsyms_lookup(wchan, NULL, NULL, NULL, namebuf);
- if (sym_name)
- return sprintf(buffer, "%s", sym_name);
- return sprintf(buffer, "%lu", wchan);
+ if (lookup_symbol_name(wchan, symname) < 0)
+ return sprintf(buffer, "%lu", wchan);
+ else
+ return sprintf(buffer, "%s", symname);
}
#endif /* CONFIG_KALLSYMS */
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index 3e3b92dabe3b..ae0117a95cfd 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -30,6 +30,8 @@ extern int sprint_symbol(char *buffer, unsigned long address);
/* Look up a kernel symbol and print it to the kernel messages. */
extern void __print_symbol(const char *fmt, unsigned long address);
+int lookup_symbol_name(unsigned long addr, char *symname);
+
#else /* !CONFIG_KALLSYMS */
static inline unsigned long kallsyms_lookup_name(const char *name)
@@ -58,6 +60,11 @@ static inline int sprint_symbol(char *buffer, unsigned long addr)
return 0;
}
+static inline int lookup_symbol_name(unsigned long addr, char *symname)
+{
+ return -ERANGE;
+}
+
/* Stupid that this does nothing, but I didn't create this mess. */
#define __print_symbol(fmt, addr)
#endif /*CONFIG_KALLSYMS*/
diff --git a/include/linux/module.h b/include/linux/module.h
index 58d5a10cdf0d..099ae5932c68 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -454,6 +454,7 @@ const char *module_address_lookup(unsigned long addr,
unsigned long *symbolsize,
unsigned long *offset,
char **modname);
+int lookup_module_symbol_name(unsigned long addr, char *symname);
/* For extable.c to search modules' exception tables. */
const struct exception_table_entry *search_module_extables(unsigned long addr);
@@ -525,6 +526,11 @@ static inline const char *module_address_lookup(unsigned long addr,
return NULL;
}
+static inline int lookup_module_symbol_name(unsigned long addr, char *symname)
+{
+ return -ERANGE;
+}
+
static inline int module_get_kallsym(unsigned int symnum, unsigned long *value,
char *type, char *name,
char *module_name, int *exported)
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index f66da025cb7f..4e2ec191a127 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -269,6 +269,23 @@ const char *kallsyms_lookup(unsigned long addr,
return NULL;
}
+int lookup_symbol_name(unsigned long addr, char *symname)
+{
+ symname[0] = '\0';
+ symname[KSYM_NAME_LEN] = '\0';
+
+ if (is_ksym_addr(addr)) {
+ unsigned long pos;
+
+ pos = get_symbol_pos(addr, NULL, NULL);
+ /* Grab name */
+ kallsyms_expand_symbol(get_symbol_offset(pos), symname);
+ return 0;
+ }
+ /* see if it's in a module */
+ return lookup_module_symbol_name(addr, symname);
+}
+
/* Look up a kernel symbol and return it in a text buffer. */
int sprint_symbol(char *buffer, unsigned long address)
{
diff --git a/kernel/module.c b/kernel/module.c
index bf4dccadf7b8..3da76ad32d78 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2126,6 +2126,29 @@ const char *module_address_lookup(unsigned long addr,
return NULL;
}
+int lookup_module_symbol_name(unsigned long addr, char *symname)
+{
+ struct module *mod;
+
+ mutex_lock(&module_mutex);
+ list_for_each_entry(mod, &modules, list) {
+ if (within(addr, mod->module_init, mod->init_size) ||
+ within(addr, mod->module_core, mod->core_size)) {
+ const char *sym;
+
+ sym = get_ksymbol(mod, addr, NULL, NULL);
+ if (!sym)
+ goto out;
+ strlcpy(symname, sym, KSYM_NAME_LEN + 1);
+ mutex_unlock(&module_mutex);
+ return 0;
+ }
+ }
+out:
+ mutex_unlock(&module_mutex);
+ return -ERANGE;
+}
+
int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
char *name, char *module_name, int *exported)
{
diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index fe9314a89f20..b734ca4bc75e 100644
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -38,15 +38,12 @@ DECLARE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases);
static void print_name_offset(struct seq_file *m, void *sym)
{
- unsigned long addr = (unsigned long)sym;
- char namebuf[KSYM_NAME_LEN+1];
- const char *sym_name;
+ char symname[KSYM_NAME_LEN+1];
- sym_name = kallsyms_lookup(addr, NULL, NULL, NULL, namebuf);
- if (sym_name)
- SEQ_printf(m, "%s", sym_name);
- else
+ if (lookup_symbol_name((unsigned long)sym, symname) < 0)
SEQ_printf(m, "<%p>", sym);
+ else
+ SEQ_printf(m, "%s", symname);
}
static void
diff --git a/kernel/time/timer_stats.c b/kernel/time/timer_stats.c
index 946ed45f7d2f..868f1bceb07f 100644
--- a/kernel/time/timer_stats.c
+++ b/kernel/time/timer_stats.c
@@ -257,14 +257,12 @@ void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
static void print_name_offset(struct seq_file *m, unsigned long addr)
{
- char namebuf[KSYM_NAME_LEN+1];
- const char *sym_name;
+ char symname[KSYM_NAME_LEN+1];
- sym_name = kallsyms_lookup(addr, NULL, NULL, NULL, namebuf);
- if (sym_name)
- seq_printf(m, "%s", sym_name);
- else
+ if (lookup_symbol_name(addr, symname) < 0)
seq_printf(m, "<%p>", (void *)addr);
+ else
+ seq_printf(m, "%s", symname);
}
static int tstats_show(struct seq_file *m, void *v)