2024-02-01 12:19:11

by Dan Carpenter

Subject: [PATCH] smb: client: Fix a double lock bug in smb2_reconnect()

This goto will try to lock spin_lock(&ses->ses_lock) twice which will
lead to a deadlock.

Fixes: 17525952fa83 ("cifs: make sure that channel scaling is done only once")
Signed-off-by: Dan Carpenter <[email protected]>
---
fs/smb/client/smb2pdu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index 2837fc4465a7..dcd3f6f08c7f 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -401,7 +401,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,

spin_lock(&ses->ses_lock);
if (ses->flags & CIFS_SES_FLAG_SCALE_CHANNELS)
- goto skip_add_channels;
+ goto skip_add_channels_locked;
ses->flags |= CIFS_SES_FLAG_SCALE_CHANNELS;
spin_unlock(&ses->ses_lock);

@@ -448,6 +448,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,

skip_add_channels:
spin_lock(&ses->ses_lock);
+skip_add_channels_locked:
ses->flags &= ~CIFS_SES_FLAG_SCALE_CHANNELS;
spin_unlock(&ses->ses_lock);

--
2.43.0

2024-02-01 18:08:45

by Steve French

Subject: Re: [PATCH] smb: client: Fix a double lock bug in smb2_reconnect()

This (and a loosely related problem were already fixed in an updated
version of that patch (updated in cifs-2.6.git for-next yesterday);
https://git.samba.org/?p=sfrench/cifs-2.6.git;a=commit;h=ee36a3b345c433a846effcdcfba437c2298eeda5


On Thu, Feb 1, 2024 at 6:19 AM Dan Carpenter <[email protected]> wrote:
>
> This goto will try to lock spin_lock(&ses->ses_lock) twice which will
> lead to a deadlock.
>
> Fixes: 17525952fa83 ("cifs: make sure that channel scaling is done only once")
> Signed-off-by: Dan Carpenter <[email protected]>
> ---
> fs/smb/client/smb2pdu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
> index 2837fc4465a7..dcd3f6f08c7f 100644
> --- a/fs/smb/client/smb2pdu.c
> +++ b/fs/smb/client/smb2pdu.c
> @@ -401,7 +401,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
>
> spin_lock(&ses->ses_lock);
> if (ses->flags & CIFS_SES_FLAG_SCALE_CHANNELS)
> - goto skip_add_channels;
> + goto skip_add_channels_locked;
> ses->flags |= CIFS_SES_FLAG_SCALE_CHANNELS;
> spin_unlock(&ses->ses_lock);
>
> @@ -448,6 +448,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
>
> skip_add_channels:
> spin_lock(&ses->ses_lock);
> +skip_add_channels_locked:
> ses->flags &= ~CIFS_SES_FLAG_SCALE_CHANNELS;
> spin_unlock(&ses->ses_lock);
>
> --
> 2.43.0
>
>


--
Thanks,

Steve