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From: Nicolas Iooss <nicolas.iooss@m4x.org>
To: selinux@vger.kernel.org
Subject: [PATCH 1/1] libsepol: do not use uninitialized value for low_value
Date: Sun,  3 Feb 2019 12:01:52 +0100	[thread overview]
Message-ID: <20190203110152.15064-1-nicolas.iooss@m4x.org> (raw)

clang's static analyzer reports a warning when low_bit is used without
having been initialized in statements such as:

    low_value = low_bit << 8;

The warning is: "Result of operation is garbage or undefined".

This is caused by low_bit being only initialized when in_range is true.
This issue is not critical because low_value is only used in an
"if (in_range)" block. Silence this warning by moving low_value's
assignment inside this block.

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
---
 libsepol/src/kernel_to_cil.c | 4 ++--
 libsepol/src/module_to_cil.c | 4 ++--
 libsepol/src/util.c          | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/libsepol/src/kernel_to_cil.c b/libsepol/src/kernel_to_cil.c
index 63e4d4899758..cd3554e8dfd9 100644
--- a/libsepol/src/kernel_to_cil.c
+++ b/libsepol/src/kernel_to_cil.c
@@ -1614,8 +1614,8 @@ static char *xperms_to_str(avtab_extended_perms_t *xperms)
 
 		if (xperms->specified & AVTAB_XPERMS_IOCTLFUNCTION) {
 			value = xperms->driver<<8 | bit;
-			low_value = xperms->driver<<8 | low_bit;
 			if (in_range) {
+				low_value = xperms->driver<<8 | low_bit;
 				len = snprintf(p, remaining, " (range 0x%hx 0x%hx)", low_value, value);
 				in_range = 0;
 			} else {
@@ -1623,8 +1623,8 @@ static char *xperms_to_str(avtab_extended_perms_t *xperms)
 			}
 		} else if (xperms->specified & AVTAB_XPERMS_IOCTLDRIVER) {
 			value = bit << 8;
-			low_value = low_bit << 8;
 			if (in_range) {
+				low_value = low_bit << 8;
 				len = snprintf(p, remaining, " (range 0x%hx 0x%hx)", low_value, (uint16_t) (value|0xff));
 				in_range = 0;
 			} else {
diff --git a/libsepol/src/module_to_cil.c b/libsepol/src/module_to_cil.c
index 4cb44e0ee657..f04589edaeff 100644
--- a/libsepol/src/module_to_cil.c
+++ b/libsepol/src/module_to_cil.c
@@ -655,8 +655,8 @@ static int xperms_to_cil(const av_extended_perms_t *xperms)
 
 		if (xperms->specified & AVTAB_XPERMS_IOCTLFUNCTION) {
 			value = xperms->driver<<8 | bit;
-			low_value = xperms->driver<<8 | low_bit;
 			if (in_range) {
+				low_value = xperms->driver<<8 | low_bit;
 				cil_printf("(range 0x%hx 0x%hx)", low_value, value);
 				in_range = 0;
 			} else {
@@ -664,8 +664,8 @@ static int xperms_to_cil(const av_extended_perms_t *xperms)
 			}
 		} else if (xperms->specified & AVTAB_XPERMS_IOCTLDRIVER) {
 			value = bit << 8;
-			low_value = low_bit << 8;
 			if (in_range) {
+				low_value = low_bit << 8;
 				cil_printf("(range 0x%hx 0x%hx)", low_value, (uint16_t) (value|0xff));
 				in_range = 0;
 			} else {
diff --git a/libsepol/src/util.c b/libsepol/src/util.c
index b00251c69aa5..a4008882b94b 100644
--- a/libsepol/src/util.c
+++ b/libsepol/src/util.c
@@ -159,16 +159,16 @@ char *sepol_extended_perms_to_string(avtab_extended_perms_t *xperms)
 
 		if (xperms->specified & AVTAB_XPERMS_IOCTLFUNCTION) {
 			value = xperms->driver<<8 | bit;
-			low_value = xperms->driver<<8 | low_bit;
 			if (in_range) {
+				low_value = xperms->driver<<8 | low_bit;
 				len = snprintf(p, sizeof(xpermsbuf) - xpermslen, "0x%hx-0x%hx ", low_value, value);
 			} else {
 				len = snprintf(p, sizeof(xpermsbuf) - xpermslen, "0x%hx ", value);
 			}
 		} else if (xperms->specified & AVTAB_XPERMS_IOCTLDRIVER) {
 			value = bit << 8;
-			low_value = low_bit << 8;
 			if (in_range) {
+				low_value = low_bit << 8;
 				len = snprintf(p, sizeof(xpermsbuf) - xpermslen, "0x%hx-0x%hx ", low_value, (uint16_t) (value|0xff));
 			} else {
 				len = snprintf(p, sizeof(xpermsbuf) - xpermslen, "0x%hx-0x%hx ", value, (uint16_t) (value|0xff));
-- 
2.20.1


             reply	other threads:[~2019-02-03 11:02 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-03 11:01 Nicolas Iooss [this message]
2019-02-04 16:54 ` [Non-DoD Source] [PATCH 1/1] libsepol: do not use uninitialized value for low_value jwcart2
2019-02-06  8:12   ` Petr Lautrbach

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