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

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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: Ross Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Ross Lagerwall 2019-01-08 18:30:56 +00:00 committed by Steve French
parent 15bc77f94e
commit 92a8109e4d
2 changed files with 12 additions and 0 deletions
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8
fs/cifs/file.c
View File

@ -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);

4
fs/cifs/smb2file.c
View File

@ -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) {