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authorAlexey Dobriyan <adobriyan@gmail.com>2018-04-10 16:31:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-11 10:28:33 -0700
commit24b2ec21192c963c17a1b687b6171e95e8b59c06 (patch)
treeb306741760dc34e5c408055ddf84fb9d253ebdb4 /fs/proc
parentd0f02231222b313d1b49278cd2e3c7e7406fea6d (diff)
downloadlinux-24b2ec21192c963c17a1b687b6171e95e8b59c06.tar.bz2
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 <adobriyan@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
-rw-r--r--fs/proc/base.c13
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 */