[PATCH 5.12 018/363] fs: dlm: change allocation limits

From: Greg Kroah-Hartman
Date: Mon May 17 2021 - 10:05:47 EST


From: Alexander Aring <aahringo@xxxxxxxxxx>

[ Upstream commit c45674fbdda138814ca21138475219c96fa5aa1f ]

While running tcpkill I experienced invalid header length values while
receiving to check that a node doesn't try to send a invalid dlm message
we also check on applications minimum allocation limit. Also use
DEFAULT_BUFFER_SIZE as maximum allocation limit. The define
LOWCOMMS_MAX_TX_BUFFER_LEN is to calculate maximum buffer limits on
application layer, future midcomms layer will subtract their needs from
this define.

Signed-off-by: Alexander Aring <aahringo@xxxxxxxxxx>
Signed-off-by: David Teigland <teigland@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/dlm/lowcomms.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 0f7fa23cccf0..f827d0b3962a 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -1375,9 +1375,11 @@ void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
struct writequeue_entry *e;
int offset = 0;

- if (len > LOWCOMMS_MAX_TX_BUFFER_LEN) {
- BUILD_BUG_ON(PAGE_SIZE < LOWCOMMS_MAX_TX_BUFFER_LEN);
+ if (len > DEFAULT_BUFFER_SIZE ||
+ len < sizeof(struct dlm_header)) {
+ BUILD_BUG_ON(PAGE_SIZE < DEFAULT_BUFFER_SIZE);
log_print("failed to allocate a buffer of size %d", len);
+ WARN_ON(1);
return NULL;
}

--
2.30.2