diff options
| author | Alexey Dobriyan <[email protected]> | 2018-04-10 16:31:30 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2018-04-11 10:28:33 -0700 |
| commit | 24b2ec21192c963c17a1b687b6171e95e8b59c06 (patch) | |
| tree | b306741760dc34e5c408055ddf84fb9d253ebdb4 | |
| parent | d0f02231222b313d1b49278cd2e3c7e7406fea6d (diff) | |
proc: check permissions earlier for /proc/*/wchan
get_wchan() accesses stack page before permissions are checked, let's
not play this game.
Link: http://lkml.kernel.org/r/20180217071923.GA16074@avx2
Signed-off-by: Alexey Dobriyan <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | fs/proc/base.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index d53246863cfb..d8b5a1653444 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -388,14 +388,17 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns, unsigned long wchan; char symname[KSYM_NAME_LEN]; - wchan = get_wchan(task); + if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) + goto print0; - if (wchan && ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS) - && !lookup_symbol_name(wchan, symname)) + wchan = get_wchan(task); + if (wchan && !lookup_symbol_name(wchan, symname)) { seq_printf(m, "%s", symname); - else - seq_putc(m, '0'); + return 0; + } +print0: + seq_putc(m, '0'); return 0; } #endif /* CONFIG_KALLSYMS */ |