leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity

cifs: fix page reference leak with readv/writev

Browse Source 
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>
This commit is contained in:
Jérôme Glisse 2019-04-10 15:37:47 -04:00 committed by Steve French
parent 652727bbe1
commit 13f5938d82
2 changed files with 23 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
fs/cifs/file.c
View File

@ -2877,7 +2877,6 @@ static void collect_uncached_write_data(struct cifs_aio_ctx *ctx)
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);
@ -2941,10 +2940,6 @@ 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);
@ -3582,7 +3577,6 @@ collect_uncached_read_data(struct cifs_aio_ctx *ctx)
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);
@ -3666,15 +3660,8 @@ 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);
}
/* mask nodata case */
if (rc == -ENODATA)

23
fs/cifs/misc.c
View File

@ -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 *refcount)
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);
}