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Message-ID: <0af9cbc4-a410-44f3-affc-a09e5c41ccd4@embeddedor.com>
Date: Fri, 26 Sep 2025 11:00:35 +0200
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To: John Meneghini <jmeneghi@...hat.com>, hare@...e.de, kbusch@...nel.org,
martin.petersen@...cle.com, linux-nvme@...ts.infradead.org,
linux-scsi@...r.kernel.org
Cc: bgurney@...hat.com, axboe@...nel.dk, emilne@...hat.com,
gustavoars@...nel.org, hch@....de, james.smart@...adcom.com,
kees@...nel.org, linux-hardening@...r.kernel.org, njavali@...vell.com,
sagi@...mberg.me
Subject: Re: [PATCH v10 11/11] scsi: qla2xxx: Fix 2 memcpy field-spanning
write issue
Hi,
Shouldn't this patch be removed from this series, since it's going to be
reverted anyways?
Thanks
-Gustavo
On 9/26/25 02:02, John Meneghini wrote:
> From: "Gustavo A. R. Silva" <gustavoars@...nel.org>
>
> purex_item.iocb is defined as a 64-element u8 array, but 64 is the
> minimum size and it can be allocated larger. This makes it a standard
> empty flex array.
>
> This was motivated by field-spanning write warnings during FPIN testing.
>
> > kernel: memcpy: detected field-spanning write (size 60) of single
> > field "((uint8_t *)fpin_pkt + buffer_copy_offset)"
> > at drivers/scsi/qla2xxx/qla_isr.c:1221 (size 44)
>
> I removed the outer wrapper from the iocb flex array, so that it can be
> linked to `purex_item.size` with `__counted_by`.
>
> These changes remove the default minimum 64-byte allocation, requiring
> further changes.
>
> In `struct scsi_qla_host` the embedded `default_item` is now followed
> by `__default_item_iocb[QLA_DEFAULT_PAYLOAD_SIZE]` to reserve space
> that will be used as `default_item.iocb`. This is wrapped using the
> `TRAILING_OVERLAP()` macro helper, which effectively creates a union
> between flexible-array member `default_item.iocb` and
> `__default_item_iocb`.
>
> Since `struct pure_item` now contains a flexible-array member, the
> helper must be placed at the end of `struct scsi_qla_host` to prevent
> a `-Wflex-array-member-not-at-end` warning.
>
> `qla24xx_alloc_purex_item()` is adjusted to no longer expect the
> default minimum size to be part of `sizeof(struct purex_item)`,
> the entire flexible array size is added to the structure size for
> allocation.
>
> This also slightly changes the layout of the purex_item struct, as
> 2-bytes of padding are added between `size` and `iocb`. The resulting
> size is the same, but iocb is shifted 2-bytes (the original `purex_item`
> structure was padded at the end, after the 64-byte defined array size).
> I don't think this is a problem.
>
> In qla_os.c:qla24xx_process_purex_rdp()
>
> To avoid a null pointer dereference the vha->default_item should be set
> to 0 last if the item pointer passed to the function matches. Also use
> a local variable to avoid multiple de-referencing of the item.
>
> Tested-by: Bryan Gurney <bgurney@...hat.com>
> Co-developed-by: Chris Leech <cleech@...hat.com>
> Signed-off-by: Chris Leech <cleech@...hat.com>
> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
> ---
> drivers/scsi/qla2xxx/qla_def.h | 10 ++++++----
> drivers/scsi/qla2xxx/qla_isr.c | 17 ++++++++---------
> drivers/scsi/qla2xxx/qla_nvme.c | 2 +-
> drivers/scsi/qla2xxx/qla_os.c | 9 ++++++---
> 4 files changed, 21 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/scsi/qla2xxx/qla_def.h b/drivers/scsi/qla2xxx/qla_def.h
> index cb95b7b12051..604e66bead1e 100644
> --- a/drivers/scsi/qla2xxx/qla_def.h
> +++ b/drivers/scsi/qla2xxx/qla_def.h
> @@ -4890,9 +4890,7 @@ struct purex_item {
> struct purex_item *pkt);
> atomic_t in_use;
> uint16_t size;
> - struct {
> - uint8_t iocb[64];
> - } iocb;
> + uint8_t iocb[] __counted_by(size);
> };
>
> #include "qla_edif.h"
> @@ -5101,7 +5099,6 @@ typedef struct scsi_qla_host {
> struct list_head head;
> spinlock_t lock;
> } purex_list;
> - struct purex_item default_item;
>
> struct name_list_extended gnl;
> /* Count of active session/fcport */
> @@ -5130,6 +5127,11 @@ typedef struct scsi_qla_host {
> #define DPORT_DIAG_IN_PROGRESS BIT_0
> #define DPORT_DIAG_CHIP_RESET_IN_PROGRESS BIT_1
> uint16_t dport_status;
> +
> + /* Must be last --ends in a flexible-array member. */
> + TRAILING_OVERLAP(struct purex_item, default_item, iocb,
> + uint8_t __default_item_iocb[QLA_DEFAULT_PAYLOAD_SIZE];
> + );
> } scsi_qla_host_t;
>
> struct qla27xx_image_status {
> diff --git a/drivers/scsi/qla2xxx/qla_isr.c b/drivers/scsi/qla2xxx/qla_isr.c
> index 8ff8781dae47..ccb044693dcb 100644
> --- a/drivers/scsi/qla2xxx/qla_isr.c
> +++ b/drivers/scsi/qla2xxx/qla_isr.c
> @@ -1078,17 +1078,17 @@ static struct purex_item *
> qla24xx_alloc_purex_item(scsi_qla_host_t *vha, uint16_t size)
> {
> struct purex_item *item = NULL;
> - uint8_t item_hdr_size = sizeof(*item);
>
> if (size > QLA_DEFAULT_PAYLOAD_SIZE) {
> - item = kzalloc(item_hdr_size +
> - (size - QLA_DEFAULT_PAYLOAD_SIZE), GFP_ATOMIC);
> + item = kzalloc(struct_size(item, iocb, size), GFP_ATOMIC);
> } else {
> if (atomic_inc_return(&vha->default_item.in_use) == 1) {
> item = &vha->default_item;
> goto initialize_purex_header;
> } else {
> - item = kzalloc(item_hdr_size, GFP_ATOMIC);
> + item = kzalloc(
> + struct_size(item, iocb, QLA_DEFAULT_PAYLOAD_SIZE),
> + GFP_ATOMIC);
> }
> }
> if (!item) {
> @@ -1128,17 +1128,16 @@ qla24xx_queue_purex_item(scsi_qla_host_t *vha, struct purex_item *pkt,
> * @vha: SCSI driver HA context
> * @pkt: ELS packet
> */
> -static struct purex_item
> -*qla24xx_copy_std_pkt(struct scsi_qla_host *vha, void *pkt)
> +static struct purex_item *
> +qla24xx_copy_std_pkt(struct scsi_qla_host *vha, void *pkt)
> {
> struct purex_item *item;
>
> - item = qla24xx_alloc_purex_item(vha,
> - QLA_DEFAULT_PAYLOAD_SIZE);
> + item = qla24xx_alloc_purex_item(vha, QLA_DEFAULT_PAYLOAD_SIZE);
> if (!item)
> return item;
>
> - memcpy(&item->iocb, pkt, sizeof(item->iocb));
> + memcpy(&item->iocb, pkt, QLA_DEFAULT_PAYLOAD_SIZE);
> return item;
> }
>
> diff --git a/drivers/scsi/qla2xxx/qla_nvme.c b/drivers/scsi/qla2xxx/qla_nvme.c
> index 8ee2e337c9e1..92488890bc04 100644
> --- a/drivers/scsi/qla2xxx/qla_nvme.c
> +++ b/drivers/scsi/qla2xxx/qla_nvme.c
> @@ -1308,7 +1308,7 @@ void qla2xxx_process_purls_iocb(void **pkt, struct rsp_que **rsp)
>
> ql_dbg(ql_dbg_unsol, vha, 0x2121,
> "PURLS OP[%01x] size %d xchg addr 0x%x portid %06x\n",
> - item->iocb.iocb[3], item->size, uctx->exchange_address,
> + item->iocb[3], item->size, uctx->exchange_address,
> fcport->d_id.b24);
> /* +48 0 1 2 3 4 5 6 7 8 9 A B C D E F
> * ----- -----------------------------------------------
> diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
> index d4b484c0fd9d..32437bae1a30 100644
> --- a/drivers/scsi/qla2xxx/qla_os.c
> +++ b/drivers/scsi/qla2xxx/qla_os.c
> @@ -6459,9 +6459,12 @@ void qla24xx_process_purex_rdp(struct scsi_qla_host *vha,
> void
> qla24xx_free_purex_item(struct purex_item *item)
> {
> - if (item == &item->vha->default_item)
> - memset(&item->vha->default_item, 0, sizeof(struct purex_item));
> - else
> + scsi_qla_host_t *base_vha = item->vha;
> +
> + if (item == &base_vha->default_item) {
> + memset(&base_vha->__default_item_iocb, 0, QLA_DEFAULT_PAYLOAD_SIZE);
> + memset(&base_vha->default_item, 0, sizeof(struct purex_item));
> + } else
> kfree(item);
> }
>
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