From: Jérôme Glisse jglisse@redhat.com
commit 13f5938d8264b5501368523c4513ff26608a33e8 upstream.
CIFS can leak pages reference gotten through GUP (get_user_pages*() through iov_iter_get_pages()). This happen if cifs_send_async_read() or cifs_write_from_iter() calls fail from within __cifs_readv() and __cifs_writev() respectively. This patch move page unreference to cifs_aio_ctx_release() which will happens on all code paths this is all simpler to follow for correctness.
Signed-off-by: Jérôme Glisse jglisse@redhat.com Cc: Steve French sfrench@samba.org Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Cc: Alexander Viro viro@zeniv.linux.org.uk Cc: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Stable stable@vger.kernel.org Signed-off-by: Steve French stfrench@microsoft.com Reviewed-by: Pavel Shilovsky pshilov@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/cifs/file.c | 15 +-------------- fs/cifs/misc.c | 23 ++++++++++++++++++++++- 2 files changed, 23 insertions(+), 15 deletions(-)
--- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -2796,7 +2796,6 @@ static void collect_uncached_write_data( struct cifs_tcon *tcon; struct cifs_sb_info *cifs_sb; struct dentry *dentry = ctx->cfile->dentry; - unsigned int i; int rc;
tcon = tlink_tcon(ctx->cfile->tlink); @@ -2860,10 +2859,6 @@ restart_loop: kref_put(&wdata->refcount, cifs_uncached_writedata_release); }
- if (!ctx->direct_io) - for (i = 0; i < ctx->npages; i++) - put_page(ctx->bv[i].bv_page); - cifs_stats_bytes_written(tcon, ctx->total_len); set_bit(CIFS_INO_INVALID_MAPPING, &CIFS_I(dentry->d_inode)->flags);
@@ -3472,7 +3467,6 @@ collect_uncached_read_data(struct cifs_a struct iov_iter *to = &ctx->iter; struct cifs_sb_info *cifs_sb; struct cifs_tcon *tcon; - unsigned int i; int rc;
tcon = tlink_tcon(ctx->cfile->tlink); @@ -3556,15 +3550,8 @@ again: kref_put(&rdata->refcount, cifs_uncached_readdata_release); }
- if (!ctx->direct_io) { - for (i = 0; i < ctx->npages; i++) { - if (ctx->should_dirty) - set_page_dirty(ctx->bv[i].bv_page); - put_page(ctx->bv[i].bv_page); - } - + if (!ctx->direct_io) ctx->total_len = ctx->len - iov_iter_count(to); - }
cifs_stats_bytes_read(tcon, ctx->total_len);
--- a/fs/cifs/misc.c +++ b/fs/cifs/misc.c @@ -789,6 +789,11 @@ cifs_aio_ctx_alloc(void) { struct cifs_aio_ctx *ctx;
+ /* + * Must use kzalloc to initialize ctx->bv to NULL and ctx->direct_io + * to false so that we know when we have to unreference pages within + * cifs_aio_ctx_release() + */ ctx = kzalloc(sizeof(struct cifs_aio_ctx), GFP_KERNEL); if (!ctx) return NULL; @@ -807,7 +812,23 @@ cifs_aio_ctx_release(struct kref *refcou struct cifs_aio_ctx, refcount);
cifsFileInfo_put(ctx->cfile); - kvfree(ctx->bv); + + /* + * ctx->bv is only set if setup_aio_ctx_iter() was call successfuly + * which means that iov_iter_get_pages() was a success and thus that + * we have taken reference on pages. + */ + if (ctx->bv) { + unsigned i; + + for (i = 0; i < ctx->npages; i++) { + if (ctx->should_dirty) + set_page_dirty(ctx->bv[i].bv_page); + put_page(ctx->bv[i].bv_page); + } + kvfree(ctx->bv); + } + kfree(ctx); }