path: root/fs/udf/file.c
diff options
authorJan Kara <jack@suse.cz>2017-06-13 15:54:58 +0200
committerJan Kara <jack@suse.cz>2017-06-14 11:21:01 +0200
commit9795e0e8ac0d6a3ee092f1b555b284b57feef99e (patch)
treece1fa5f47b7b24d04d4893528eae522ce1885023 /fs/udf/file.c
parenta247f7236d06f504e57637b8ec124fc1af226d08 (diff)
udf: Fix races with i_size changes during readpage
__udf_adinicb_readpage() uses i_size several times. When truncate changes i_size while the function is running, it can observe several different values and thus e.g. expose uninitialized parts of page to userspace. Also use i_size_read() in the function since it does not hold inode_lock. Since i_size is guaranteed to be small, this cannot really cause any issues even on 32-bit archs but let's be careful. CC: stable@vger.kernel.org Fixes: 9c2fc0de1a6e638fe58c354a463f544f42a90a09 Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/udf/file.c')
1 files changed, 7 insertions, 2 deletions
diff --git a/fs/udf/file.c b/fs/udf/file.c
index f5eb2d5b3bac..e06d2c15749a 100644
--- a/fs/udf/file.c
+++ b/fs/udf/file.c
@@ -43,10 +43,15 @@ static void __udf_adinicb_readpage(struct page *page)
struct inode *inode = page->mapping->host;
char *kaddr;
struct udf_inode_info *iinfo = UDF_I(inode);
+ loff_t isize = i_size_read(inode);
+ /*
+ * We have to be careful here as truncate can change i_size under us.
+ * So just sample it once and use the same value everywhere.
+ */
kaddr = kmap_atomic(page);
- memcpy(kaddr, iinfo->i_ext.i_data + iinfo->i_lenEAttr, inode->i_size);
- memset(kaddr + inode->i_size, 0, PAGE_SIZE - inode->i_size);
+ memcpy(kaddr, iinfo->i_ext.i_data + iinfo->i_lenEAttr, isize);
+ memset(kaddr + isize, 0, PAGE_SIZE - isize);