[PATCH net-next] wwan: iosm: use a flexible array rather than allocate short objects

[PATCH net-next] wwan: iosm: use a flexible array rather than allocate short objects

[Jakub Kicinski]

GCC array-bounds warns that ipc_coredump_get_list() under-allocates
the size of struct iosm_cd_table *cd_table.

This is avoidable - we just need a flexible array. Nothing calls
sizeof() on struct iosm_cd_list or anything that contains it.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: m.chetan.kumar@intel.com
CC: linuxwwan@intel.com
CC: loic.poulain@linaro.org
CC: ryazanov.s.a@gmail.com
CC: johannes@sipsolutions.net
---
 drivers/net/wwan/iosm/iosm_ipc_coredump.h | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/net/wwan/iosm/iosm_ipc_coredump.h b/drivers/net/wwan/iosm/iosm_ipc_coredump.h
index 0809ba664276..3da5ec75e0f0 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_coredump.h
+++ b/drivers/net/wwan/iosm/iosm_ipc_coredump.h
@@ -14,9 +14,6 @@
 /* Max buffer allocated to receive coredump data */
 #define MAX_DATA_SIZE 0x00010000
 
-/* Max number of file entries */
-#define MAX_NOF_ENTRY 256
-
 /* Max length */
 #define MAX_SIZE_LEN 32
 
@@ -38,7 +35,7 @@ struct iosm_cd_list_entry {
  */
 struct iosm_cd_list {
 	__le32 num_entries;
-	struct iosm_cd_list_entry entry[MAX_NOF_ENTRY];
+	struct iosm_cd_list_entry entry[];
 } __packed;
 
 /**
-- 
2.34.3

Re: [PATCH net-next] wwan: iosm: use a flexible array rather than allocate short objects

[Jakub Kicinski]

On Thu, 19 May 2022 23:00:13 -0700 Jakub Kicinski wrote:
> GCC array-bounds warns that ipc_coredump_get_list() under-allocates
> the size of struct iosm_cd_table *cd_table.
> 
> This is avoidable - we just need a flexible array. Nothing calls
> sizeof() on struct iosm_cd_list or anything that contains it.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Coincidentally IDK if this:

int ipc_coredump_get_list(struct iosm_devlink *devlink, u16 cmd)

	if (byte_read != MAX_CD_LIST_SIZE)
		goto cd_init_fail;

shouldn't set ret before jumping? Maybe set it to 0 if it's okay for 
it to be zero to make that clear?

RE: [PATCH net-next] wwan: iosm: use a flexible array rather than allocate short objects

[Kumar, M Chetan]

> -----Original Message-----
> From: Jakub Kicinski <kuba@kernel.org>
> Sent: Friday, May 20, 2022 11:34 AM
> To: davem@davemloft.net
> Cc: netdev@vger.kernel.org; edumazet@google.com; pabeni@redhat.com;
> Kumar, M Chetan <m.chetan.kumar@intel.com>; linuxwwan
> <linuxwwan@intel.com>; loic.poulain@linaro.org; ryazanov.s.a@gmail.com;
> johannes@sipsolutions.net
> Subject: Re: [PATCH net-next] wwan: iosm: use a flexible array rather than
> allocate short objects
> 
> On Thu, 19 May 2022 23:00:13 -0700 Jakub Kicinski wrote:
> > GCC array-bounds warns that ipc_coredump_get_list() under-allocates
> > the size of struct iosm_cd_table *cd_table.
> >
> > This is avoidable - we just need a flexible array. Nothing calls
> > sizeof() on struct iosm_cd_list or anything that contains it.
> >
> > Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> 
> Coincidentally IDK if this:
> 
> int ipc_coredump_get_list(struct iosm_devlink *devlink, u16 cmd)
> 
> 	if (byte_read != MAX_CD_LIST_SIZE)
> 		goto cd_init_fail;
> 
> shouldn't set ret before jumping? Maybe set it to 0 if it's okay for it to be zero
> to make that clear?

This is a redundant check we can remove it.
If the byte_read is less than MAX_CD_LIST_SIZE an error is returned as part of previous ret
check.

RE: [PATCH net-next] wwan: iosm: use a flexible array rather than allocate short objects

[Kumar, M Chetan]

> -----Original Message-----
> From: Jakub Kicinski <kuba@kernel.org>
> Sent: Friday, May 20, 2022 11:30 AM
> To: davem@davemloft.net
> Cc: netdev@vger.kernel.org; edumazet@google.com; pabeni@redhat.com;
> Jakub Kicinski <kuba@kernel.org>; Kumar, M Chetan
> <m.chetan.kumar@intel.com>; linuxwwan <linuxwwan@intel.com>;
> loic.poulain@linaro.org; ryazanov.s.a@gmail.com;
> johannes@sipsolutions.net
> Subject: [PATCH net-next] wwan: iosm: use a flexible array rather than
> allocate short objects
> 
> GCC array-bounds warns that ipc_coredump_get_list() under-allocates the
> size of struct iosm_cd_table *cd_table.
> 
> This is avoidable - we just need a flexible array. Nothing calls
> sizeof() on struct iosm_cd_list or anything that contains it.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Reviewed-by: M Chetan Kumar <m.chetan.kumar@intel.com>

Re: [PATCH net-next] wwan: iosm: use a flexible array rather than allocate short objects

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 19 May 2022 23:00:13 -0700 you wrote:
> GCC array-bounds warns that ipc_coredump_get_list() under-allocates
> the size of struct iosm_cd_table *cd_table.
> 
> This is avoidable - we just need a flexible array. Nothing calls
> sizeof() on struct iosm_cd_list or anything that contains it.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> 
> [...]

Here is the summary with links:
  - [net-next] wwan: iosm: use a flexible array rather than allocate short objects
    https://git.kernel.org/netdev/net-next/c/eac67d83bf25

You are awesome, thank you!
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