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Commit 48f90917 authored by Peter Kalauskas's avatar Peter Kalauskas
Browse files

UPSTREAM: drivers/block/zram/zram_drv.c: fix bug storing backing_dev 



The call to strlcpy in backing_dev_store is incorrect. It should take
the size of the destination buffer instead of the size of the source
buffer.  Additionally, ignore the newline character (\n) when reading
the new file_name buffer. This makes it possible to set the backing_dev
as follows:

	echo /dev/sdX > /sys/block/zram0/backing_dev

The reason it worked before was the fact that strlcpy() copies 'len - 1'
bytes, which is strlen(buf) - 1 in our case, so it accidentally didn't
copy the trailing new line symbol.  Which also means that "echo -n
/dev/sdX" most likely was broken.

Signed-off-by: default avatarPeter Kalauskas <peskal@google.com>
Link: http://lkml.kernel.org/r/20180813061623.GC64836@rodete-desktop-imager.corp.google.com


Acked-by: default avatarMinchan Kim <minchan@kernel.org>
Reviewed-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: <stable@vger.kernel.org>    [4.14+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>

(cherry picked from commit c8bd134a4bddafe5917d163eea73873932c15e83)
Signed-off-by: default avatarPeter Kalauskas <peskal@google.com>
Bug: 112488418
Change-Id: I9033aa53aed83ce83df7b00e1676bb0db65ed753
parent 6a1b5923

drivers/block/zram/zram_drv.c

+6 −1
Original line number Original line Diff line number Diff line
@@ -339,6 +339,7 @@ static ssize_t backing_dev_store(struct device *dev, 
		struct device_attribute *attr, const char *buf, size_t len)

		struct device_attribute *attr, const char *buf, size_t len)

{

{

	char *file_name;

	char *file_name;

	size_t sz;

	struct file *backing_dev = NULL;

	struct file *backing_dev = NULL;

	struct inode *inode;

	struct inode *inode;

	struct address_space *mapping;

	struct address_space *mapping;
@@ -360,7 +361,11 @@ static ssize_t backing_dev_store(struct device *dev, 
		goto out;

		goto out;

	}

	}





	strlcpy(file_name, buf, len);

	strlcpy(file_name, buf, PATH_MAX);

	/* ignore trailing newline */

	sz = strlen(file_name);

	if (sz > 0 && file_name[sz - 1] == '\n')

		file_name[sz - 1] = 0x00;





	backing_dev = filp_open(file_name, O_RDWR|O_LARGEFILE, 0);

	backing_dev = filp_open(file_name, O_RDWR|O_LARGEFILE, 0);

	if (IS_ERR(backing_dev)) {

	if (IS_ERR(backing_dev)) {