From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tao Ma Date: Fri, 28 Sep 2012 15:07:40 +0800 Subject: [Ocfs2-devel] [PATCH] ocfs2: fix NULL pointer dereference in ocfs2_duplicate_clusters_by_page In-Reply-To: <1348815422-1868-1-git-send-email-tiger.yang@oracle.com> References: <1348815422-1868-1-git-send-email-tiger.yang@oracle.com> Message-ID: <50654CBC.3020406@tao.ma> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ocfs2-devel@oss.oracle.com Hi Tiger, Interesting. why we never find it in the old reflink test? A little big strange. Could you please tell me the test case to trigger this issue? Another thing I want to say is that now your patch removes all the readahead during CoW. Why? If you want to avoid the dereference of a NULL pointer, I guess just skip the call of ocfs2_readahead_for_cow if file = NULL should work? Thanks Tao On 09/28/2012 02:57 PM, Tiger Yang wrote: > Since ocfs2_cow_file_pos will invoke ocfs2_refcount_cow with a NULL > as the struct file pointer, it finally result in a null pointer > dereference in ocfs2_duplicate_clusters_by_page. > This patch replace file pointer with inode pointer in > cow_duplicate_clusters to fix this issue. > > Signed-off-by: Tiger Yang > --- > fs/ocfs2/aops.c | 2 +- > fs/ocfs2/file.c | 6 ++-- > fs/ocfs2/move_extents.c | 2 +- > fs/ocfs2/refcounttree.c | 53 +++++++--------------------------------------- > fs/ocfs2/refcounttree.h | 6 ++-- > 5 files changed, 16 insertions(+), 53 deletions(-) > > diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c > index 6577432..8cc8cad 100644 > --- a/fs/ocfs2/aops.c > +++ b/fs/ocfs2/aops.c > @@ -1755,7 +1755,7 @@ try_again: > goto out; > } else if (ret == 1) { > clusters_need = wc->w_clen; > - ret = ocfs2_refcount_cow(inode, filp, di_bh, > + ret = ocfs2_refcount_cow(inode, di_bh, > wc->w_cpos, wc->w_clen, UINT_MAX); > if (ret) { > mlog_errno(ret); > diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c > index 46a1f6d..e26cd20 100644 > --- a/fs/ocfs2/file.c > +++ b/fs/ocfs2/file.c > @@ -370,7 +370,7 @@ static int ocfs2_cow_file_pos(struct inode *inode, > if (!(ext_flags & OCFS2_EXT_REFCOUNTED)) > goto out; > > - return ocfs2_refcount_cow(inode, NULL, fe_bh, cpos, 1, cpos+1); > + return ocfs2_refcount_cow(inode, fe_bh, cpos, 1, cpos+1); > > out: > return status; > @@ -899,7 +899,7 @@ static int ocfs2_zero_extend_get_range(struct inode *inode, > zero_clusters = last_cpos - zero_cpos; > > if (needs_cow) { > - rc = ocfs2_refcount_cow(inode, NULL, di_bh, zero_cpos, > + rc = ocfs2_refcount_cow(inode, di_bh, zero_cpos, > zero_clusters, UINT_MAX); > if (rc) { > mlog_errno(rc); > @@ -2097,7 +2097,7 @@ static int ocfs2_prepare_inode_for_refcount(struct inode *inode, > > *meta_level = 1; > > - ret = ocfs2_refcount_cow(inode, file, di_bh, cpos, clusters, UINT_MAX); > + ret = ocfs2_refcount_cow(inode, di_bh, cpos, clusters, UINT_MAX); > if (ret) > mlog_errno(ret); > out: > diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c > index 6083432..8519926 100644 > --- a/fs/ocfs2/move_extents.c > +++ b/fs/ocfs2/move_extents.c > @@ -69,7 +69,7 @@ static int __ocfs2_move_extent(handle_t *handle, > u64 ino = ocfs2_metadata_cache_owner(context->et.et_ci); > u64 old_blkno = ocfs2_clusters_to_blocks(inode->i_sb, p_cpos); > > - ret = ocfs2_duplicate_clusters_by_page(handle, context->file, cpos, > + ret = ocfs2_duplicate_clusters_by_page(handle, inode, cpos, > p_cpos, new_p_cpos, len); > if (ret) { > mlog_errno(ret); > diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c > index 30a0550..2d1bb91 100644 > --- a/fs/ocfs2/refcounttree.c > +++ b/fs/ocfs2/refcounttree.c > @@ -49,7 +49,6 @@ > > struct ocfs2_cow_context { > struct inode *inode; > - struct file *file; > u32 cow_start; > u32 cow_len; > struct ocfs2_extent_tree data_et; > @@ -66,7 +65,7 @@ struct ocfs2_cow_context { > u32 *num_clusters, > unsigned int *extent_flags); > int (*cow_duplicate_clusters)(handle_t *handle, > - struct file *file, > + struct inode *inode, > u32 cpos, u32 old_cluster, > u32 new_cluster, u32 new_len); > }; > @@ -2922,14 +2921,12 @@ static int ocfs2_clear_cow_buffer(handle_t *handle, struct buffer_head *bh) > } > > int ocfs2_duplicate_clusters_by_page(handle_t *handle, > - struct file *file, > + struct inode *inode, > u32 cpos, u32 old_cluster, > u32 new_cluster, u32 new_len) > { > int ret = 0, partial; > - struct inode *inode = file->f_path.dentry->d_inode; > - struct ocfs2_caching_info *ci = INODE_CACHE(inode); > - struct super_block *sb = ocfs2_metadata_cache_get_super(ci); > + struct super_block *sb = inode->i_sb; > u64 new_block = ocfs2_clusters_to_blocks(sb, new_cluster); > struct page *page; > pgoff_t page_index; > @@ -2973,13 +2970,6 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle, > if (PAGE_CACHE_SIZE <= OCFS2_SB(sb)->s_clustersize) > BUG_ON(PageDirty(page)); > > - if (PageReadahead(page)) { > - page_cache_async_readahead(mapping, > - &file->f_ra, file, > - page, page_index, > - readahead_pages); > - } > - > if (!PageUptodate(page)) { > ret = block_read_full_page(page, ocfs2_get_block); > if (ret) { > @@ -2999,7 +2989,8 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle, > } > } > > - ocfs2_map_and_dirty_page(inode, handle, from, to, > + ocfs2_map_and_dirty_page(inode, > + handle, from, to, > page, 0, &new_block); > mark_page_accessed(page); > unlock: > @@ -3015,12 +3006,11 @@ unlock: > } > > int ocfs2_duplicate_clusters_by_jbd(handle_t *handle, > - struct file *file, > + struct inode *inode, > u32 cpos, u32 old_cluster, > u32 new_cluster, u32 new_len) > { > int ret = 0; > - struct inode *inode = file->f_path.dentry->d_inode; > struct super_block *sb = inode->i_sb; > struct ocfs2_caching_info *ci = INODE_CACHE(inode); > int i, blocks = ocfs2_clusters_to_blocks(sb, new_len); > @@ -3145,7 +3135,7 @@ static int ocfs2_replace_clusters(handle_t *handle, > > /*If the old clusters is unwritten, no need to duplicate. */ > if (!(ext_flags & OCFS2_EXT_UNWRITTEN)) { > - ret = context->cow_duplicate_clusters(handle, context->file, > + ret = context->cow_duplicate_clusters(handle, context->inode, > cpos, old, new, len); > if (ret) { > mlog_errno(ret); > @@ -3423,35 +3413,12 @@ static int ocfs2_replace_cow(struct ocfs2_cow_context *context) > return ret; > } > > -static void ocfs2_readahead_for_cow(struct inode *inode, > - struct file *file, > - u32 start, u32 len) > -{ > - struct address_space *mapping; > - pgoff_t index; > - unsigned long num_pages; > - int cs_bits = OCFS2_SB(inode->i_sb)->s_clustersize_bits; > - > - if (!file) > - return; > - > - mapping = file->f_mapping; > - num_pages = (len << cs_bits) >> PAGE_CACHE_SHIFT; > - if (!num_pages) > - num_pages = 1; > - > - index = ((loff_t)start << cs_bits) >> PAGE_CACHE_SHIFT; > - page_cache_sync_readahead(mapping, &file->f_ra, file, > - index, num_pages); > -} > - > /* > * Starting at cpos, try to CoW write_len clusters. Don't CoW > * past max_cpos. This will stop when it runs into a hole or an > * unrefcounted extent. > */ > static int ocfs2_refcount_cow_hunk(struct inode *inode, > - struct file *file, > struct buffer_head *di_bh, > u32 cpos, u32 write_len, u32 max_cpos) > { > @@ -3480,8 +3447,6 @@ static int ocfs2_refcount_cow_hunk(struct inode *inode, > > BUG_ON(cow_len == 0); > > - ocfs2_readahead_for_cow(inode, file, cow_start, cow_len); > - > context = kzalloc(sizeof(struct ocfs2_cow_context), GFP_NOFS); > if (!context) { > ret = -ENOMEM; > @@ -3503,7 +3468,6 @@ static int ocfs2_refcount_cow_hunk(struct inode *inode, > context->ref_root_bh = ref_root_bh; > context->cow_duplicate_clusters = ocfs2_duplicate_clusters_by_page; > context->get_clusters = ocfs2_di_get_clusters; > - context->file = file; > > ocfs2_init_dinode_extent_tree(&context->data_et, > INODE_CACHE(inode), di_bh); > @@ -3532,7 +3496,6 @@ out: > * clusters between cpos and cpos+write_len are safe to modify. > */ > int ocfs2_refcount_cow(struct inode *inode, > - struct file *file, > struct buffer_head *di_bh, > u32 cpos, u32 write_len, u32 max_cpos) > { > @@ -3552,7 +3515,7 @@ int ocfs2_refcount_cow(struct inode *inode, > num_clusters = write_len; > > if (ext_flags & OCFS2_EXT_REFCOUNTED) { > - ret = ocfs2_refcount_cow_hunk(inode, file, di_bh, cpos, > + ret = ocfs2_refcount_cow_hunk(inode, di_bh, cpos, > num_clusters, max_cpos); > if (ret) { > mlog_errno(ret); > diff --git a/fs/ocfs2/refcounttree.h b/fs/ocfs2/refcounttree.h > index 7754608..6422bbc 100644 > --- a/fs/ocfs2/refcounttree.h > +++ b/fs/ocfs2/refcounttree.h > @@ -53,7 +53,7 @@ int ocfs2_prepare_refcount_change_for_del(struct inode *inode, > int *credits, > int *ref_blocks); > int ocfs2_refcount_cow(struct inode *inode, > - struct file *filep, struct buffer_head *di_bh, > + struct buffer_head *di_bh, > u32 cpos, u32 write_len, u32 max_cpos); > > typedef int (ocfs2_post_refcount_func)(struct inode *inode, > @@ -85,11 +85,11 @@ int ocfs2_refcount_cow_xattr(struct inode *inode, > u32 cpos, u32 write_len, > struct ocfs2_post_refcount *post); > int ocfs2_duplicate_clusters_by_page(handle_t *handle, > - struct file *file, > + struct inode *inode, > u32 cpos, u32 old_cluster, > u32 new_cluster, u32 new_len); > int ocfs2_duplicate_clusters_by_jbd(handle_t *handle, > - struct file *file, > + struct inode *inode, > u32 cpos, u32 old_cluster, > u32 new_cluster, u32 new_len); > int ocfs2_cow_sync_writeback(struct super_block *sb, >