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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2015-11-04 02:04:04 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-11-04 02:04:04 +0300 |
| commit | 7eeef2abe87dc0d8c276f97ccfdb1f42d9d1e4d8 (patch) | |
| tree | 69141bc10fab1bb9b8aaa94f87c617b9c813155c /fs/proc | |
| parent | 6aa2fdb87cf01d7746955c600cbac352dc04d451 (diff) | |
| parent | b2f73922d119686323f14fbbe46587f863852328 (diff) | |
| download | linux-7eeef2abe87dc0d8c276f97ccfdb1f42d9d1e4d8.tar.xz | |
Merge branch 'core-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull wchan kernel address hiding from Ingo Molnar:
"This fixes a wchan related information leak in /proc/PID/stat.
There's a bit of an ABI twist to it: instead of setting the wchan
field to 0 (which is our usual technique) we set it conditionally to a
0/1 flag to keep ABI compatibility with older procps versions that
only fetches /proc/PID/wchan (symbolic names) if the absolute wchan
address is nonzero"
* 'core-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
fs/proc, core/debug: Don't expose absolute kernel addresses via wchan
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/array.c | 16 | ||||
| -rw-r--r-- | fs/proc/base.c | 9 |
2 files changed, 17 insertions, 8 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c index f60f0121e331..eed2050db9be 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -375,7 +375,7 @@ int proc_pid_status(struct seq_file *m, struct pid_namespace *ns, static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *task, int whole) { - unsigned long vsize, eip, esp, wchan = ~0UL; + unsigned long vsize, eip, esp, wchan = 0; int priority, nice; int tty_pgrp = -1, tty_nr = 0; sigset_t sigign, sigcatch; @@ -507,7 +507,19 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, seq_put_decimal_ull(m, ' ', task->blocked.sig[0] & 0x7fffffffUL); seq_put_decimal_ull(m, ' ', sigign.sig[0] & 0x7fffffffUL); seq_put_decimal_ull(m, ' ', sigcatch.sig[0] & 0x7fffffffUL); - seq_put_decimal_ull(m, ' ', wchan); + + /* + * We used to output the absolute kernel address, but that's an + * information leak - so instead we show a 0/1 flag here, to signal + * to user-space whether there's a wchan field in /proc/PID/wchan. + * + * This works with older implementations of procps as well. + */ + if (wchan) + seq_puts(m, " 1"); + else + seq_puts(m, " 0"); + seq_put_decimal_ull(m, ' ', 0); seq_put_decimal_ull(m, ' ', 0); seq_put_decimal_ll(m, ' ', task->exit_signal); diff --git a/fs/proc/base.c b/fs/proc/base.c index b25eee4cead5..29595af32866 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -430,13 +430,10 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns, wchan = get_wchan(task); - if (lookup_symbol_name(wchan, symname) < 0) { - if (!ptrace_may_access(task, PTRACE_MODE_READ)) - return 0; - seq_printf(m, "%lu", wchan); - } else { + if (wchan && ptrace_may_access(task, PTRACE_MODE_READ) && !lookup_symbol_name(wchan, symname)) seq_printf(m, "%s", symname); - } + else + seq_putc(m, '0'); return 0; } |