From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>,
linux-kernel@vger.kernel.org,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
stable@vger.kernel.org
Subject: [GIT PULL 3/3] intel_th: msu: Fix an off-by-one in attribute store
Date: Fri, 14 Dec 2018 17:53:47 +0200 [thread overview]
Message-ID: <20181214155347.75722-4-alexander.shishkin@linux.intel.com> (raw)
In-Reply-To: <20181214155347.75722-1-alexander.shishkin@linux.intel.com>
The 'nr_pages' attribute of the 'msc' subdevices parses a comma-separated
list of window sizes, passed from userspace. However, there is a bug in
the string parsing logic wherein it doesn't exclude the comma character
from the range of characters as it consumes them. This leads to an
out-of-bounds access given a sufficiently long list. For example:
> # echo 8,8,8,8 > /sys/bus/intel_th/devices/0-msc0/nr_pages
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in memchr+0x1e/0x40
> Read of size 1 at addr ffff8803ffcebcd1 by task sh/825
>
> CPU: 3 PID: 825 Comm: npktest.sh Tainted: G W 4.20.0-rc1+
> Call Trace:
> dump_stack+0x7c/0xc0
> print_address_description+0x6c/0x23c
> ? memchr+0x1e/0x40
> kasan_report.cold.5+0x241/0x308
> memchr+0x1e/0x40
> nr_pages_store+0x203/0xd00 [intel_th_msu]
Fix this by accounting for the comma character.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Fixes: ba82664c134ef ("intel_th: Add Memory Storage Unit driver")
Cc: stable@vger.kernel.org # v4.4+
---
drivers/hwtracing/intel_th/msu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c
index d293e55553bd..ba7aaf421f36 100644
--- a/drivers/hwtracing/intel_th/msu.c
+++ b/drivers/hwtracing/intel_th/msu.c
@@ -1423,7 +1423,8 @@ nr_pages_store(struct device *dev, struct device_attribute *attr,
if (!end)
break;
- len -= end - p;
+ /* consume the number and the following comma, hence +1 */
+ len -= end - p + 1;
p = end + 1;
} while (len);
--
2.19.2
prev parent reply other threads:[~2018-12-14 15:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-14 15:53 [GIT PULL 0/3] stm class/intel_th: Fixes for v4.20 Alexander Shishkin
2018-12-14 15:53 ` [GIT PULL 1/3] stm class: Fix a module refcount leak in policy creation error path Alexander Shishkin
2018-12-19 8:49 ` Greg Kroah-Hartman
2018-12-19 11:45 ` Alexander Shishkin
2018-12-19 12:34 ` Greg Kroah-Hartman
2018-12-19 11:46 ` [PATCH] " Alexander Shishkin
2018-12-14 15:53 ` [GIT PULL 2/3] stm class: Add a reference to the SyS-T document Alexander Shishkin
2018-12-14 15:53 ` Alexander Shishkin [this message]
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