diff options
| author | Alexandra Winter <wintera@linux.ibm.com> | 2026-09-28 17:14:20 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-09-30 17:36:00 -0700 |
| commit | a0227fa24e8a2a0397cc4eb669731ff8d9161bbd (patch) | |
| tree | 25cb9ffdc55333ebbb4cc3afbee73f7780090993 /include/linux | |
| parent | 22691f0128a0155abc997eb10e108809599d7ebd (diff) | |
| download | linux-a0227fa24e8a2a0397cc4eb669731ff8d9161bbd.tar.gz linux-a0227fa24e8a2a0397cc4eb669731ff8d9161bbd.zip | |
s390/ism: Zerorize dmb at allocation
Sashiko reported [1] that 'Missing __GFP_ZERO in folio_alloc() causes
uninitialized kernel memory to be exposed in the receive message buffer'.
An ism dmb is receive-only, so the data is not leaked to a remote peer.
In general the smc kernel module (dibs client) will only push newly
received data to userspace. We still should not have uninitialized data
in a receive buffer.
Since
commit 750afb08ca71 ("cross-tree: phase out dma_zalloc_coherent()")
dma_alloc_coherent no longer required the __GFP_ZERO flag, but when
commit 83781384a96b ("s390/ism: Properly fix receive message buffer allocation")
switched to folio_alloc(), it should have added back the __GFP_ZERO flag.
Add __GFP_ZERO flag and state in dibs.h that register_dbm() provides
a zerorized buffer (dibs_lo already does).
Link: https://lore.kernel.org/linux-s390/20260903143746.A5CC41F00A3A@smtp.kernel.org/ [1]
Fixes: 83781384a96b ("s390/ism: Properly fix receive message buffer allocation")
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Reviewed-by: Julian Ruess <julianr@linux.ibm.com>
Link: https://patch.msgid.link/20260928151420.383105-1-wintera@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/dibs.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/dibs.h b/include/linux/dibs.h index d3e0777f25ae..0c10c224bcca 100644 --- a/include/linux/dibs.h +++ b/include/linux/dibs.h @@ -261,12 +261,12 @@ struct dibs_dev_ops { * @vlan_id: deprecated, ignored if device does not support vlan * Upon return in addition the following fields will be valid: * @dmb_tok: for usage by remote and local devices and clients - * @cpu_addr: allocated buffer + * @cpu_addr: allocated, zerorized buffer * @idx: dmb index, unique per dibs device * @dma_addr: to be used by device driver,if applicable * - * Allocate a dmb buffer and register it with this device and for this - * client. + * Allocate and zerorize a dmb buffer and register it with this device + * and for this client. * Return: zero on success */ int (*register_dmb)(struct dibs_dev *dev, struct dibs_dmb *dmb, |