The patch titled
Subject: drivers/block/zram/zram_drv.c: fix bug storing backing_dev
has been added to the -mm tree. Its filename is
zram-fix-bug-storing-backing_dev.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/zram-fix-bug-storing-backing_dev.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/zram-fix-bug-storing-backing_dev.patch
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------------------------------------------------------
From: Peter Kalauskas <peskal@xxxxxxxxxx>
Subject: 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: Peter Kalauskas <peskal@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/20180813061623.GC64836@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [4.14+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/drivers/block/zram/zram_drv.c~zram-fix-bug-storing-backing_dev
+++ a/drivers/block/zram/zram_drv.c
@@ -337,6 +337,7 @@ static ssize_t backing_dev_store(struct
struct device_attribute *attr, const char *buf, size_t len)
{
char *file_name;
+ size_t sz;
struct file *backing_dev = NULL;
struct inode *inode;
struct address_space *mapping;
@@ -357,7 +358,11 @@ static ssize_t backing_dev_store(struct
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);
if (IS_ERR(backing_dev)) {
_
Patches currently in -mm which might be from peskal@xxxxxxxxxx are
zram-fix-bug-storing-backing_dev.patch
