Commit 3f3e47cf authored Dec 06, 2014 by Raviv Shvili Committed by Subhash Jadavani May 31, 2016

mmc: core : fix arbitrary read/write to user space



In the MMC card debug_fs the read and write handlers use the strlcat
and sscanf, without checking the pointer given.
Since the pointer is not checked it is possible to write
everywhere (ring 0 or 3).
In order to fix it, an access_ok function is being used to verify
the buffer's pointer supplied by user is valid.

CRs-fixed: 545716
Change-Id: Ia710b6af5a95974fc930ca902e8ff18afa4e17ba
Signed-off-by: Raviv Shvili <rshvili@codeaurora.org>
[merez@codeaurora.org: Fixed conflicts due to missing BKOPS statistics]
Signed-off-by: Maya Erez <merez@codeaurora.org>

parent a35f5e1c

drivers/mmc/core/debugfs.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -15,6 +15,7 @@
		#include <linux/slab.h>
		#include <linux/stat.h>
		#include <linux/fault-inject.h>
		#include <linux/uaccess.h>

		#include <linux/mmc/card.h>
		#include <linux/mmc/host.h>
		@@ -424,6 +425,9 @@ static ssize_t mmc_wr_pack_stats_read(struct file filp, char __user ubuf,
		if (!card)
		return cnt;

		if (!access_ok(VERIFY_WRITE, ubuf, cnt))
		return cnt;

		if (!card->wr_pack_stats.print_in_read)
		return 0;

		@@ -564,6 +568,9 @@ static ssize_t mmc_wr_pack_stats_write(struct file *filp,
		if (!card)
		return cnt;

		if (!access_ok(VERIFY_READ, ubuf, cnt))
		return cnt;

		sscanf(ubuf, "%d", &value);
		if (value) {
		mmc_blk_init_packed_statistics(card);