From: Alexey Dobriyan <adobriyan@xxxxxxxxx> Subject: 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@xxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx> Cc: Rasmus Villemoes <rasmus.villemoes@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/base.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff -puN fs/proc/base.c~proc-check-permissions-earlier-for-proc-wchan fs/proc/base.c --- a/fs/proc/base.c~proc-check-permissions-earlier-for-proc-wchan +++ a/fs/proc/base.c @@ -388,14 +388,17 @@ static int proc_pid_wchan(struct seq_fil 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 */ _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
