This is a note to let you know that I've just added the patch titled
smb: Fix regression in writes when non-standard maximum write size negotiated
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
smb-fix-regression-in-writes-when-non-standard-maximum-write-size-negotiated.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4860abb91f3d7fbaf8147d54782149bb1fc45892 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@xxxxxxxxxxxxx>
Date: Tue, 6 Feb 2024 16:34:22 -0600
Subject: smb: Fix regression in writes when non-standard maximum write size negotiated
From: Steve French <stfrench@xxxxxxxxxxxxx>
commit 4860abb91f3d7fbaf8147d54782149bb1fc45892 upstream.
The conversion to netfs in the 6.3 kernel caused a regression when
maximum write size is set by the server to an unexpected value which is
not a multiple of 4096 (similarly if the user overrides the maximum
write size by setting mount parm "wsize", but sets it to a value that
is not a multiple of 4096). When negotiated write size is not a
multiple of 4096 the netfs code can skip the end of the final
page when doing large sequential writes, causing data corruption.
This section of code is being rewritten/removed due to a large
netfs change, but until that point (ie for the 6.3 kernel until now)
we can not support non-standard maximum write sizes.
Add a warning if a user specifies a wsize on mount that is not
a multiple of 4096 (and round down), also add a change where we
round down the maximum write size if the server negotiates a value
that is not a multiple of 4096 (we also have to check to make sure that
we do not round it down to zero).
Reported-by: R. Diez" <rdiez-2006@xxxxxxx>
Fixes: d08089f649a0 ("cifs: Change the I/O paths to use an iterator rather than a page list")
Suggested-by: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx>
Acked-by: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx>
Tested-by: Matthew Ruffell <matthew.ruffell@xxxxxxxxxxxxx>
Reviewed-by: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v6.3+
Cc: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/smb/client/connect.c | 14 ++++++++++++--
fs/smb/client/fs_context.c | 11 +++++++++++
2 files changed, 23 insertions(+), 2 deletions(-)
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -3426,8 +3426,18 @@ int cifs_mount_get_tcon(struct cifs_moun
* the user on mount
*/
if ((cifs_sb->ctx->wsize == 0) ||
- (cifs_sb->ctx->wsize > server->ops->negotiate_wsize(tcon, ctx)))
- cifs_sb->ctx->wsize = server->ops->negotiate_wsize(tcon, ctx);
+ (cifs_sb->ctx->wsize > server->ops->negotiate_wsize(tcon, ctx))) {
+ cifs_sb->ctx->wsize =
+ round_down(server->ops->negotiate_wsize(tcon, ctx), PAGE_SIZE);
+ /*
+ * in the very unlikely event that the server sent a max write size under PAGE_SIZE,
+ * (which would get rounded down to 0) then reset wsize to absolute minimum eg 4096
+ */
+ if (cifs_sb->ctx->wsize == 0) {
+ cifs_sb->ctx->wsize = PAGE_SIZE;
+ cifs_dbg(VFS, "wsize too small, reset to minimum ie PAGE_SIZE, usually 4096\n");
+ }
+ }
if ((cifs_sb->ctx->rsize == 0) ||
(cifs_sb->ctx->rsize > server->ops->negotiate_rsize(tcon, ctx)))
cifs_sb->ctx->rsize = server->ops->negotiate_rsize(tcon, ctx);
--- a/fs/smb/client/fs_context.c
+++ b/fs/smb/client/fs_context.c
@@ -1107,6 +1107,17 @@ static int smb3_fs_context_parse_param(s
case Opt_wsize:
ctx->wsize = result.uint_32;
ctx->got_wsize = true;
+ if (ctx->wsize % PAGE_SIZE != 0) {
+ ctx->wsize = round_down(ctx->wsize, PAGE_SIZE);
+ if (ctx->wsize == 0) {
+ ctx->wsize = PAGE_SIZE;
+ cifs_dbg(VFS, "wsize too small, reset to minimum %ld\n", PAGE_SIZE);
+ } else {
+ cifs_dbg(VFS,
+ "wsize rounded down to %d to multiple of PAGE_SIZE %ld\n",
+ ctx->wsize, PAGE_SIZE);
+ }
+ }
break;
case Opt_acregmax:
ctx->acregmax = HZ * result.uint_32;
Patches currently in stable-queue which might be from stfrench@xxxxxxxxxxxxx are
queue-6.6/smb-client-set-correct-id-uid-and-cruid-for-multiuser-automounts.patch
queue-6.6/smb-fix-regression-in-writes-when-non-standard-maximum-write-size-negotiated.patch
queue-6.6/cifs-fix-underflow-in-parse_server_interfaces.patch
queue-6.6/ksmbd-free-aux-buffer-if-ksmbd_iov_pin_rsp_read-fails.patch
