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CIFS: Fix too big maxBuf size for SMB3 mounts

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SMB3 servers can respond with MaxTransactSize of more than 4M
that can cause a memory allocation error returned from kmalloc
in a lock codepath. Also the client doesn't support multicredit
requests now and allows buffer sizes of 65536 bytes only. Set
MaxTransactSize to this maximum supported value.

Cc: stable@vger.kernel.org # 3.7+
Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
This commit is contained in:
Pavel Shilovsky 2014-02-14 13:31:02 +04:00 committed by Steve French
parent 5d81de8e86
commit 2365c4eaf0
3 changed files with 10 additions and 11 deletions
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3
fs/cifs/smb2glob.h
View file

@ -57,4 +57,7 @@
#define SMB2_CMACAES_SIZE (16)
#define SMB3_SIGNKEY_SIZE (16)
/* Maximum buffer size value we can send with 1 credit */
#define SMB2_MAX_BUFFER_SIZE 65536
#endif /* _SMB2_GLOB_H */

14
fs/cifs/smb2ops.c
View file

@ -182,11 +182,8 @@ smb2_negotiate_wsize(struct cifs_tcon *tcon, struct smb_vol *volume_info)
/* start with specified wsize, or default */
wsize = volume_info->wsize ? volume_info->wsize : CIFS_DEFAULT_IOSIZE;
wsize = min_t(unsigned int, wsize, server->max_write);
/*
* limit write size to 2 ** 16, because we don't support multicredit
* requests now.
*/
wsize = min_t(unsigned int, wsize, 2 << 15);
/* set it to the maximum buffer size value we can send with 1 credit */
wsize = min_t(unsigned int, wsize, SMB2_MAX_BUFFER_SIZE);
return wsize;
}
@ -200,11 +197,8 @@ smb2_negotiate_rsize(struct cifs_tcon *tcon, struct smb_vol *volume_info)
/* start with specified rsize, or default */
rsize = volume_info->rsize ? volume_info->rsize : CIFS_DEFAULT_IOSIZE;
rsize = min_t(unsigned int, rsize, server->max_read);
/*
* limit write size to 2 ** 16, because we don't support multicredit
* requests now.
*/
rsize = min_t(unsigned int, rsize, 2 << 15);
/* set it to the maximum buffer size value we can send with 1 credit */
rsize = min_t(unsigned int, rsize, SMB2_MAX_BUFFER_SIZE);
return rsize;
}

4
fs/cifs/smb2pdu.c
View file

@ -413,7 +413,9 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
/* SMB2 only has an extended negflavor */
server->negflavor = CIFS_NEGFLAVOR_EXTENDED;
server->maxBuf = le32_to_cpu(rsp->MaxTransactSize);
/* set it to the maximum buffer size value we can send with 1 credit */
server->maxBuf = min_t(unsigned int, le32_to_cpu(rsp->MaxTransactSize),
SMB2_MAX_BUFFER_SIZE);
server->max_read = le32_to_cpu(rsp->MaxReadSize);
server->max_write = le32_to_cpu(rsp->MaxWriteSize);
/* BB Do we need to validate the SecurityMode? */