From: Jérôme Glisse <jglisse@xxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Steve French <sfrench@xxxxxxxxx>
Cc: linux-cifs@xxxxxxxxxxxxxxx
Cc: samba-technical@xxxxxxxxxxxxxxx
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Reviewed-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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);
}
