2021-02-14 23:52:57

by Tong Zhang

Subject: [PATCH v1] atm: idt77252: fix build broken on amd64

idt77252 is broken and wont load on amd64 systems
modprobe idt77252 shows the following

idt77252_init: skb->cb is too small (48 < 56)

Add packed attribute to struct idt77252_skb_prv and struct atm_skb_data
so that the total size can be <= sizeof(skb->cb)
Also convert runtime size check to buildtime size check in
idt77252_init()

Signed-off-by: Tong Zhang <[email protected]>
---
drivers/atm/idt77252.c | 11 +----------
drivers/atm/idt77252.h | 2 +-
include/linux/atmdev.h | 2 +-
3 files changed, 3 insertions(+), 12 deletions(-)

diff --git a/drivers/atm/idt77252.c b/drivers/atm/idt77252.c
index 5f0472c18bcb..0c13cac903de 100644
--- a/drivers/atm/idt77252.c
+++ b/drivers/atm/idt77252.c
@@ -3743,16 +3743,7 @@ static int __init idt77252_init(void)
struct sk_buff *skb;

printk("%s: at %p\n", __func__, idt77252_init);
-
- if (sizeof(skb->cb) < sizeof(struct atm_skb_data) +
- sizeof(struct idt77252_skb_prv)) {
- printk(KERN_ERR "%s: skb->cb is too small (%lu < %lu)\n",
- __func__, (unsigned long) sizeof(skb->cb),
- (unsigned long) sizeof(struct atm_skb_data) +
- sizeof(struct idt77252_skb_prv));
- return -EIO;
- }
-
+ BUILD_BUG_ON(sizeof(skb->cb) < sizeof(struct idt77252_skb_prv) + sizeof(struct atm_skb_data));
return pci_register_driver(&idt77252_driver);
}

diff --git a/drivers/atm/idt77252.h b/drivers/atm/idt77252.h
index 9339197d701c..b059d31364dd 100644
--- a/drivers/atm/idt77252.h
+++ b/drivers/atm/idt77252.h
@@ -789,7 +789,7 @@ struct idt77252_skb_prv {
struct scqe tbd; /* Transmit Buffer Descriptor */
dma_addr_t paddr; /* DMA handle */
u32 pool; /* sb_pool handle */
-};
+} __packed;

#define IDT77252_PRV_TBD(skb) \
(((struct idt77252_skb_prv *)(ATM_SKB(skb)+1))->tbd)
diff --git a/include/linux/atmdev.h b/include/linux/atmdev.h
index d7493016cd46..60cd25c0461b 100644
--- a/include/linux/atmdev.h
+++ b/include/linux/atmdev.h
@@ -207,7 +207,7 @@ struct atm_skb_data {
struct atm_vcc *vcc; /* ATM VCC */
unsigned long atm_options; /* ATM layer options */
unsigned int acct_truesize; /* truesize accounted to vcc */
-};
+} __packed;

#define VCC_HTABLE_SIZE 32

--
2.25.1

2021-02-15 20:52:50

by patchwork-bot+netdevbpf

Subject: Re: [PATCH v1] atm: idt77252: fix build broken on amd64

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Sun, 14 Feb 2021 18:43:08 -0500 you wrote:
> idt77252 is broken and wont load on amd64 systems
> modprobe idt77252 shows the following
>
> idt77252_init: skb->cb is too small (48 < 56)
>
> Add packed attribute to struct idt77252_skb_prv and struct atm_skb_data
> so that the total size can be <= sizeof(skb->cb)
> Also convert runtime size check to buildtime size check in
> idt77252_init()
>
> [...]

Here is the summary with links:
- [v1] atm: idt77252: fix build broken on amd64
https://git.kernel.org/netdev/net/c/d0a0bbe7b0a1

You are awesome, thank you!
--
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