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| author | Jan Kara <jack@suse.cz> | 2017-06-13 15:54:58 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-07-27 15:10:20 -0700 |
| commit | 47a493225854537bf98e11502b9dcc25ed634c6b (patch) | |
| tree | 95b3e56bb93b85d2588bffe4ab9656fcd4278a45 | |
| parent | 9968e8105914ba437b98dd19200092537dfeb23b (diff) | |
| download | linux-stable-47a493225854537bf98e11502b9dcc25ed634c6b.tar.gz linux-stable-47a493225854537bf98e11502b9dcc25ed634c6b.tar.bz2 linux-stable-47a493225854537bf98e11502b9dcc25ed634c6b.zip | |
udf: Fix races with i_size changes during readpage
commit 9795e0e8ac0d6a3ee092f1b555b284b57feef99e upstream.
__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.
Fixes: 9c2fc0de1a6e638fe58c354a463f544f42a90a09
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/udf/file.c | 9 |
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); flush_dcache_page(page); SetPageUptodate(page); kunmap_atomic(kaddr); |