tjh.dev
wifi: ipw2x00: convert ipw_fw_error->elem to flexible array[]
The ipw_fw_error structure contains a payload[] flexible array as well as
two pointers to this array area, ->elem, and ->log. The total size of the
allocated structure is computed without use of the <linux/overflow.h>
macros.
There's no reason to keep both a payload[] and an extra pointer to both the
elem and log members. Convert the elem pointer member into the flexible
array member, removing payload.
Fix the allocation of the ipw_fw_error structure to use size_add(),
struct_size(), and array_size() to compute the allocation. This ensures
that any overflow saturates at SIZE_MAX rather than overflowing and
potentially allowing an undersized allocation.
Before the structure change, the layout of ipw_fw_error was:
struct ipw_fw_error {
long unsigned int jiffies; /* 0 8 */
u32 status; /* 8 4 */
u32 config; /* 12 4 */
u32 elem_len; /* 16 4 */
u32 log_len; /* 20 4 */
struct ipw_error_elem * elem; /* 24 8 */
struct ipw_event * log; /* 32 8 */
u8 payload[]; /* 40 0 */
/* size: 40, cachelines: 1, members: 8 */
/* last cacheline: 40 bytes */
};
After this change, the layout is now:
struct ipw_fw_error {
long unsigned int jiffies; /* 0 8 */
u32 status; /* 8 4 */
u32 config; /* 12 4 */
u32 elem_len; /* 16 4 */
u32 log_len; /* 20 4 */
struct ipw_event * log; /* 24 8 */
struct ipw_error_elem elem[]; /* 32 0 */
/* size: 32, cachelines: 1, members: 7 */
/* last cacheline: 32 bytes */
};
This saves a total of 8 bytes for every ipw_fw_error allocation, and
removes the risk of a potential overflow on the allocation.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Cc: Stanislav Yakovlev <stas.yakovlev@gmail.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230307230148.3735684-1-jacob.e.keller@intel.com
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