From: Marco Schlumpp <marco@unikraft.io>
Date: Mon, 17 Apr 2023 08:04:04 +0000 (+0200)
Subject: lib/posix-futex: Check for proper FUTEX_CLOCK_REALTIME usage
X-Git-Tag: RELEASE-0.13.0~68
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=7ef5bbccffa6592a0d6da0efedd3c63366ba3cbb;p=unikraft%2Funikraft.git

lib/posix-futex: Check for proper FUTEX_CLOCK_REALTIME usage

The documentation specifies a list of operations which support this
flag. This adds a check that explicitly rejects all invalid combinations
and returns `ENOSYS` according to the documentation.

Checkpatch-Ignore: ENOSYS
Signed-off-by: Marco Schlumpp <marco@unikraft.io>
Reviewed-by: Adina Smeu <adina.smeu@gmail.com>
Approved-by: Razvan Deaconescu <razvand@unikraft.io>
Tested-by: Unikraft CI <monkey@unikraft.io>
GitHub-Closes: #758
---

diff --git a/lib/posix-futex/futex.c b/lib/posix-futex/futex.c
index d8eace321..f8f579640 100644
--- a/lib/posix-futex/futex.c
+++ b/lib/posix-futex/futex.c
@@ -277,13 +277,22 @@ UK_LLSYSCALL_R_DEFINE(int, futex, uint32_t *, uaddr, int, futex_op,
 		      uint32_t *, uaddr2, uint32_t, val3)
 {
 	__nsec timeout_ns;
+ 	int cmd = futex_op & FUTEX_CMD_MASK;
+
+	/* Reject invalid combinations of the realtime clock flag */
+	if (futex_op & FUTEX_CLOCK_REALTIME && !(
+		cmd == FUTEX_WAIT ||
+		cmd == FUTEX_WAIT_BITSET ||
+		cmd == FUTEX_LOCK_PI2 ||
+		cmd == FUTEX_WAIT_REQUEUE_PI))
+		return -ENOSYS;
 
 	/*
 	 * N.B. CLOCK_(MONOTONIC|REALTIME|...) are at the moment all the same in
 	 * Unikraft. Therefore, we can just use CLOCK_MONOTONIC for timeouts in
 	 * the following code.
 	 */
-	switch (futex_op & FUTEX_CMD_MASK) {
+	switch (cmd) {
 	case FUTEX_WAIT:
 		/*
 		 * `timeout` is relative to "now" (whenever that is). To