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| author | Al Viro <viro@zeniv.linux.org.uk> | 2017-09-29 13:43:15 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2017-09-29 13:43:15 -0400 |
| commit | 6c85501f2fabcfc4fc6ed976543d252c4eaf4be9 (patch) | |
| tree | 7ae62970c63295669f955f60b78dbada3e564d30 /kernel/exit.c | |
| parent | b776e4b1a990045a7c70798f1f353c3160c26594 (diff) | |
| download | lwn-6c85501f2fabcfc4fc6ed976543d252c4eaf4be9.tar.gz lwn-6c85501f2fabcfc4fc6ed976543d252c4eaf4be9.zip | |
fix infoleak in waitid(2)
kernel_waitid() can return a PID, an error or 0. rusage is filled in the first
case and waitid(2) rusage should've been copied out exactly in that case, *not*
whenever kernel_waitid() has not returned an error. Compat variant shares that
braino; none of kernel_wait4() callers do, so the below ought to fix it.
Reported-and-tested-by: Alexander Potapenko <glider@google.com>
Fixes: ce72a16fa705 ("wait4(2)/waitid(2): separate copying rusage to userland")
Cc: stable@vger.kernel.org # v4.13
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'kernel/exit.c')
| -rw-r--r-- | kernel/exit.c | 23 |
1 files changed, 10 insertions, 13 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 3481ababd06a..f2cd53e92147 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1600,12 +1600,10 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, struct waitid_info info = {.status = 0}; long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL); int signo = 0; + if (err > 0) { signo = SIGCHLD; err = 0; - } - - if (!err) { if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) return -EFAULT; } @@ -1723,16 +1721,15 @@ COMPAT_SYSCALL_DEFINE5(waitid, if (err > 0) { signo = SIGCHLD; err = 0; - } - - if (!err && uru) { - /* kernel_waitid() overwrites everything in ru */ - if (COMPAT_USE_64BIT_TIME) - err = copy_to_user(uru, &ru, sizeof(ru)); - else - err = put_compat_rusage(&ru, uru); - if (err) - return -EFAULT; + if (uru) { + /* kernel_waitid() overwrites everything in ru */ + if (COMPAT_USE_64BIT_TIME) + err = copy_to_user(uru, &ru, sizeof(ru)); + else + err = put_compat_rusage(&ru, uru); + if (err) + return -EFAULT; + } } if (!infop) |