The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 547c556f4db7c09447ecf5f833ab6aaae0c5ab58 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers(a)google.com>
Date: Tue, 31 Dec 2019 12:11:49 -0600
Subject: [PATCH] ext4: fix deadlock allocating crypto bounce page from mempool
ext4_writepages() on an encrypted file has to encrypt the data, but it
can't modify the pagecache pages in-place, so it encrypts the data into
bounce pages and writes those instead. All bounce pages are allocated
from a mempool using GFP_NOFS.
This is not correct use of a mempool, and it can deadlock. This is
because GFP_NOFS includes __GFP_DIRECT_RECLAIM, which enables the "never
fail" mode for mempool_alloc() where a failed allocation will fall back
to waiting for one of the preallocated elements in the pool.
But since this mode is used for all a bio's pages and not just the
first, it can deadlock waiting for pages already in the bio to be freed.
This deadlock can be reproduced by patching mempool_alloc() to pretend
that pool->alloc() always fails (so that it always falls back to the
preallocations), and then creating an encrypted file of size > 128 KiB.
Fix it by only using GFP_NOFS for the first page in the bio. For
subsequent pages just use GFP_NOWAIT, and if any of those fail, just
submit the bio and start a new one.
This will need to be fixed in f2fs too, but that's less straightforward.
Fixes: c9af28fdd449 ("ext4 crypto: don't let data integrity writebacks fail with ENOMEM")
Cc: stable(a)vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers(a)google.com>
Link: https://lore.kernel.org/r/20191231181149.47619-1-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso(a)mit.edu>
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 24aeedb8fc75..68b39e75446a 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -512,17 +512,26 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
gfp_t gfp_flags = GFP_NOFS;
unsigned int enc_bytes = round_up(len, i_blocksize(inode));
+ /*
+ * Since bounce page allocation uses a mempool, we can only use
+ * a waiting mask (i.e. request guaranteed allocation) on the
+ * first page of the bio. Otherwise it can deadlock.
+ */
+ if (io->io_bio)
+ gfp_flags = GFP_NOWAIT | __GFP_NOWARN;
retry_encrypt:
bounce_page = fscrypt_encrypt_pagecache_blocks(page, enc_bytes,
0, gfp_flags);
if (IS_ERR(bounce_page)) {
ret = PTR_ERR(bounce_page);
- if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {
- if (io->io_bio) {
+ if (ret == -ENOMEM &&
+ (io->io_bio || wbc->sync_mode == WB_SYNC_ALL)) {
+ gfp_flags = GFP_NOFS;
+ if (io->io_bio)
ext4_io_submit(io);
- congestion_wait(BLK_RW_ASYNC, HZ/50);
- }
- gfp_flags |= __GFP_NOFAIL;
+ else
+ gfp_flags |= __GFP_NOFAIL;
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
goto retry_encrypt;
}
The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 547c556f4db7c09447ecf5f833ab6aaae0c5ab58 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers(a)google.com>
Date: Tue, 31 Dec 2019 12:11:49 -0600
Subject: [PATCH] ext4: fix deadlock allocating crypto bounce page from mempool
ext4_writepages() on an encrypted file has to encrypt the data, but it
can't modify the pagecache pages in-place, so it encrypts the data into
bounce pages and writes those instead. All bounce pages are allocated
from a mempool using GFP_NOFS.
This is not correct use of a mempool, and it can deadlock. This is
because GFP_NOFS includes __GFP_DIRECT_RECLAIM, which enables the "never
fail" mode for mempool_alloc() where a failed allocation will fall back
to waiting for one of the preallocated elements in the pool.
But since this mode is used for all a bio's pages and not just the
first, it can deadlock waiting for pages already in the bio to be freed.
This deadlock can be reproduced by patching mempool_alloc() to pretend
that pool->alloc() always fails (so that it always falls back to the
preallocations), and then creating an encrypted file of size > 128 KiB.
Fix it by only using GFP_NOFS for the first page in the bio. For
subsequent pages just use GFP_NOWAIT, and if any of those fail, just
submit the bio and start a new one.
This will need to be fixed in f2fs too, but that's less straightforward.
Fixes: c9af28fdd449 ("ext4 crypto: don't let data integrity writebacks fail with ENOMEM")
Cc: stable(a)vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers(a)google.com>
Link: https://lore.kernel.org/r/20191231181149.47619-1-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso(a)mit.edu>
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 24aeedb8fc75..68b39e75446a 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -512,17 +512,26 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
gfp_t gfp_flags = GFP_NOFS;
unsigned int enc_bytes = round_up(len, i_blocksize(inode));
+ /*
+ * Since bounce page allocation uses a mempool, we can only use
+ * a waiting mask (i.e. request guaranteed allocation) on the
+ * first page of the bio. Otherwise it can deadlock.
+ */
+ if (io->io_bio)
+ gfp_flags = GFP_NOWAIT | __GFP_NOWARN;
retry_encrypt:
bounce_page = fscrypt_encrypt_pagecache_blocks(page, enc_bytes,
0, gfp_flags);
if (IS_ERR(bounce_page)) {
ret = PTR_ERR(bounce_page);
- if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {
- if (io->io_bio) {
+ if (ret == -ENOMEM &&
+ (io->io_bio || wbc->sync_mode == WB_SYNC_ALL)) {
+ gfp_flags = GFP_NOFS;
+ if (io->io_bio)
ext4_io_submit(io);
- congestion_wait(BLK_RW_ASYNC, HZ/50);
- }
- gfp_flags |= __GFP_NOFAIL;
+ else
+ gfp_flags |= __GFP_NOFAIL;
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
goto retry_encrypt;
}
The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 114de38225d9b300f027e2aec9afbb6e0def154b Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trondmy(a)gmail.com>
Date: Sun, 2 Feb 2020 17:53:54 -0500
Subject: [PATCH] NFS: Directory page cache pages need to be locked when read
When a NFS directory page cache page is removed from the page cache,
its contents are freed through a call to nfs_readdir_clear_array().
To prevent the removal of the page cache entry until after we've
finished reading it, we must take the page lock.
Fixes: 11de3b11e08c ("NFS: Fix a memory leak in nfs_readdir")
Cc: stable(a)vger.kernel.org # v2.6.37+
Signed-off-by: Trond Myklebust <trond.myklebust(a)hammerspace.com>
Reviewed-by: Benjamin Coddington <bcodding(a)redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker(a)Netapp.com>
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 451c48cdb1c2..d95c2c94bd87 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -702,8 +702,6 @@ int nfs_readdir_filler(void *data, struct page* page)
static
void cache_page_release(nfs_readdir_descriptor_t *desc)
{
- if (!desc->page->mapping)
- nfs_readdir_clear_array(desc->page);
put_page(desc->page);
desc->page = NULL;
}
@@ -717,19 +715,28 @@ struct page *get_cache_page(nfs_readdir_descriptor_t *desc)
/*
* Returns 0 if desc->dir_cookie was found on page desc->page_index
+ * and locks the page to prevent removal from the page cache.
*/
static
-int find_cache_page(nfs_readdir_descriptor_t *desc)
+int find_and_lock_cache_page(nfs_readdir_descriptor_t *desc)
{
int res;
desc->page = get_cache_page(desc);
if (IS_ERR(desc->page))
return PTR_ERR(desc->page);
-
- res = nfs_readdir_search_array(desc);
+ res = lock_page_killable(desc->page);
if (res != 0)
- cache_page_release(desc);
+ goto error;
+ res = -EAGAIN;
+ if (desc->page->mapping != NULL) {
+ res = nfs_readdir_search_array(desc);
+ if (res == 0)
+ return 0;
+ }
+ unlock_page(desc->page);
+error:
+ cache_page_release(desc);
return res;
}
@@ -744,7 +751,7 @@ int readdir_search_pagecache(nfs_readdir_descriptor_t *desc)
desc->last_cookie = 0;
}
do {
- res = find_cache_page(desc);
+ res = find_and_lock_cache_page(desc);
} while (res == -EAGAIN);
return res;
}
@@ -783,7 +790,6 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc)
desc->eof = true;
kunmap(desc->page);
- cache_page_release(desc);
dfprintk(DIRCACHE, "NFS: nfs_do_filldir() filling ended @ cookie %Lu; returning = %d\n",
(unsigned long long)*desc->dir_cookie, res);
return res;
@@ -829,13 +835,13 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc)
status = nfs_do_filldir(desc);
+ out_release:
+ nfs_readdir_clear_array(desc->page);
+ cache_page_release(desc);
out:
dfprintk(DIRCACHE, "NFS: %s: returns %d\n",
__func__, status);
return status;
- out_release:
- cache_page_release(desc);
- goto out;
}
/* The file offset position represents the dirent entry number. A
@@ -900,6 +906,8 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
break;
res = nfs_do_filldir(desc);
+ unlock_page(desc->page);
+ cache_page_release(desc);
if (res < 0)
break;
} while (!desc->eof);
The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 4b310319c6a8ce708f1033d57145e2aa027a883c Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trondmy(a)gmail.com>
Date: Sun, 2 Feb 2020 17:53:53 -0500
Subject: [PATCH] NFS: Fix memory leaks and corruption in readdir
nfs_readdir_xdr_to_array() must not exit without having initialised
the array, so that the page cache deletion routines can safely
call nfs_readdir_clear_array().
Furthermore, we should ensure that if we exit nfs_readdir_filler()
with an error, we free up any page contents to prevent a leak
if we try to fill the page again.
Fixes: 11de3b11e08c ("NFS: Fix a memory leak in nfs_readdir")
Cc: stable(a)vger.kernel.org # v2.6.37+
Signed-off-by: Trond Myklebust <trond.myklebust(a)hammerspace.com>
Reviewed-by: Benjamin Coddington <bcodding(a)redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker(a)Netapp.com>
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 6427a8a8d61a..451c48cdb1c2 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -162,6 +162,17 @@ typedef struct {
bool eof;
} nfs_readdir_descriptor_t;
+static
+void nfs_readdir_init_array(struct page *page)
+{
+ struct nfs_cache_array *array;
+
+ array = kmap_atomic(page);
+ memset(array, 0, sizeof(struct nfs_cache_array));
+ array->eof_index = -1;
+ kunmap_atomic(array);
+}
+
/*
* we are freeing strings created by nfs_add_to_readdir_array()
*/
@@ -174,6 +185,7 @@ void nfs_readdir_clear_array(struct page *page)
array = kmap_atomic(page);
for (i = 0; i < array->size; i++)
kfree(array->array[i].string.name);
+ array->size = 0;
kunmap_atomic(array);
}
@@ -610,6 +622,8 @@ int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page,
int status = -ENOMEM;
unsigned int array_size = ARRAY_SIZE(pages);
+ nfs_readdir_init_array(page);
+
entry.prev_cookie = 0;
entry.cookie = desc->last_cookie;
entry.eof = 0;
@@ -626,8 +640,6 @@ int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page,
}
array = kmap(page);
- memset(array, 0, sizeof(struct nfs_cache_array));
- array->eof_index = -1;
status = nfs_readdir_alloc_pages(pages, array_size);
if (status < 0)
@@ -682,6 +694,7 @@ int nfs_readdir_filler(void *data, struct page* page)
unlock_page(page);
return 0;
error:
+ nfs_readdir_clear_array(page);
unlock_page(page);
return ret;
}