From: Peter Kalauskas Date: Wed, 22 Aug 2018 04:54:02 +0000 (-0700) Subject: drivers/block/zram/zram_drv.c: fix bug storing backing_dev X-Git-Tag: v5.15~8149^2~129 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=c8bd134a4bddafe5917d163eea73873932c15e83;p=mirror_ubuntu-kernels.git 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 Link: http://lkml.kernel.org/r/20180813061623.GC64836@rodete-desktop-imager.corp.google.com Acked-by: Minchan Kim Reviewed-by: Sergey Senozhatsky Cc: [4.14+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index c7acf74253a1..a1d6b5597c17 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -337,6 +337,7 @@ static ssize_t backing_dev_store(struct device *dev, 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 device *dev, 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)) {