Commit 92a8109e authored by Ross Lagerwall's avatar Ross Lagerwall Committed by Steve French
Browse files

cifs: Limit memory used by lock request calls to a page 



The code tries to allocate a contiguous buffer with a size supplied by
the server (maxBuf). This could fail if memory is fragmented since it
results in high order allocations for commonly used server
implementations. It is also wasteful since there are probably
few locks in the usual case. Limit the buffer to be no larger than a
page to avoid memory allocation failures due to fragmentation.

Signed-off-by: default avatarRoss Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 15bc77f9

fs/cifs/file.c

+8 −0
Original line number Diff line number Diff line
@@ -1140,6 +1140,10 @@ cifs_push_mandatory_locks(struct cifsFileInfo *cfile) 
		return -EINVAL;

	}



	BUILD_BUG_ON(sizeof(struct smb_hdr) + sizeof(LOCKING_ANDX_RANGE) >

		     PAGE_SIZE);

	max_buf = min_t(unsigned int, max_buf - sizeof(struct smb_hdr),

			PAGE_SIZE);

	max_num = (max_buf - sizeof(struct smb_hdr)) /

						sizeof(LOCKING_ANDX_RANGE);

	buf = kcalloc(max_num, sizeof(LOCKING_ANDX_RANGE), GFP_KERNEL);
@@ -1478,6 +1482,10 @@ cifs_unlock_range(struct cifsFileInfo *cfile, struct file_lock *flock, 
	if (!max_buf)

		return -EINVAL;



	BUILD_BUG_ON(sizeof(struct smb_hdr) + sizeof(LOCKING_ANDX_RANGE) >

		     PAGE_SIZE);

	max_buf = min_t(unsigned int, max_buf - sizeof(struct smb_hdr),

			PAGE_SIZE);

	max_num = (max_buf - sizeof(struct smb_hdr)) /

						sizeof(LOCKING_ANDX_RANGE);

	buf = kcalloc(max_num, sizeof(LOCKING_ANDX_RANGE), GFP_KERNEL);

fs/cifs/smb2file.c

+4 −0
Original line number Diff line number Diff line
@@ -128,6 +128,8 @@ smb2_unlock_range(struct cifsFileInfo *cfile, struct file_lock *flock, 
	if (!max_buf)

		return -EINVAL;



	BUILD_BUG_ON(sizeof(struct smb2_lock_element) > PAGE_SIZE);

	max_buf = min_t(unsigned int, max_buf, PAGE_SIZE);

	max_num = max_buf / sizeof(struct smb2_lock_element);

	buf = kcalloc(max_num, sizeof(struct smb2_lock_element), GFP_KERNEL);

	if (!buf)
@@ -264,6 +266,8 @@ smb2_push_mandatory_locks(struct cifsFileInfo *cfile) 
		return -EINVAL;

	}



	BUILD_BUG_ON(sizeof(struct smb2_lock_element) > PAGE_SIZE);

	max_buf = min_t(unsigned int, max_buf, PAGE_SIZE);

	max_num = max_buf / sizeof(struct smb2_lock_element);

	buf = kcalloc(max_num, sizeof(struct smb2_lock_element), GFP_KERNEL);

	if (!buf) {

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