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authorNeilBrown <neilb@suse.com>2015-08-06 01:27:55 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-10-04 21:42:22 +0300
commit65da3484d9be5664f5f7d2378e438bb2794f40b8 (patch)
tree886ed45dc33cdfd927a395fceccbe2bd3d5cc4b5 /fs/sysfs
parentcfcf6a91aa0d59faddb423a65230eea7f230d057 (diff)
downloadlinux-65da3484d9be5664f5f7d2378e438bb2794f40b8.tar.xz
sysfs: correctly handle short reads on PREALLOC attrs.
attributes declared with __ATTR_PREALLOC use sysfs_kf_read() which ignores the 'count' arg. So a 1-byte read request can return more bytes than that. This is seen with the 'dash' shell when 'read' is used on some 'md' sysfs attributes. So only return the 'min' of count and the attribute length. Signed-off-by: NeilBrown <neilb@suse.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/sysfs')
-rw-r--r--fs/sysfs/file.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 6c95628ea377..f35523d4fa3a 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -108,6 +108,7 @@ static ssize_t sysfs_kf_read(struct kernfs_open_file *of, char *buf,
{
const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
struct kobject *kobj = of->kn->parent->priv;
+ size_t len;
/*
* If buf != of->prealloc_buf, we don't know how
@@ -115,7 +116,8 @@ static ssize_t sysfs_kf_read(struct kernfs_open_file *of, char *buf,
*/
if (pos || WARN_ON_ONCE(buf != of->prealloc_buf))
return 0;
- return ops->show(kobj, of->kn->priv, buf);
+ len = ops->show(kobj, of->kn->priv, buf);
+ return min(count, len);
}
/* kernfs write callback for regular sysfs files */