From 9d65cb4a1718a072898c7a57a3bc61b2dc4bcd4d Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Tue, 8 May 2007 00:28:43 -0700 Subject: 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 Cc: Rusty Russell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/kallsyms.c | 17 +++++++++++++++++ kernel/module.c | 23 +++++++++++++++++++++++ kernel/time/timer_list.c | 11 ++++------- kernel/time/timer_stats.c | 10 ++++------ 4 files changed, 48 insertions(+), 13 deletions(-) (limited to 'kernel') 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) -- cgit v1.2.1