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authorAlexander Shishkin <alexander.shishkin@linux.intel.com>2018-12-19 17:19:22 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-12-19 20:21:06 +0100
commitec5b5ad6e272d8d6b92d1007f79574919862a2d2 (patch)
tree3d2973f90448c4ba3c36b5945642960425dd8d0a /drivers/hwtracing/intel_th/msu.c
parent4cdd41585c5196f75e1e496c4f64345b2c700e0b (diff)
intel_th: msu: Fix an off-by-one in attribute store
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+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hwtracing/intel_th/msu.c')
-rw-r--r--drivers/hwtracing/intel_th/msu.c3
1 files changed, 2 insertions, 1 deletions
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);