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wifi: ipw2x00: convert ipw_fw_error->elem to flexible array[]

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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
This commit is contained in:
Jacob Keller 2023-03-07 15:01:48 -08:00 committed by Kalle Valo
parent 0606b34402
commit a23c82e006
2 changed files with 4 additions and 6 deletions
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7
drivers/net/wireless/intel/ipw2x00/ipw2200.c
View File

@ -1234,9 +1234,9 @@ static struct ipw_fw_error *ipw_alloc_error_log(struct ipw_priv *priv)
u32 base = ipw_read32(priv, IPW_ERROR_LOG);
u32 elem_len = ipw_read_reg32(priv, base);
error = kmalloc(sizeof(*error) +
sizeof(*error->elem) * elem_len +
sizeof(*error->log) * log_len, GFP_ATOMIC);
error = kmalloc(size_add(struct_size(error, elem, elem_len),
array_size(sizeof(*error->log), log_len)),
GFP_ATOMIC);
if (!error) {
IPW_ERROR("Memory allocation for firmware error log "
"failed.\n");
@ -1247,7 +1247,6 @@ static struct ipw_fw_error *ipw_alloc_error_log(struct ipw_priv *priv)
error->config = priv->config;
error->elem_len = elem_len;
error->log_len = log_len;
error->elem = (struct ipw_error_elem *)error->payload;
error->log = (struct ipw_event *)(error->elem + elem_len);
ipw_capture_event_log(priv, log_len, error->log);

3
drivers/net/wireless/intel/ipw2x00/ipw2200.h
View File

@ -1106,9 +1106,8 @@ struct ipw_fw_error { /* XXX */
u32 config;
u32 elem_len;
u32 log_len;
struct ipw_error_elem *elem;
struct ipw_event *log;
u8 payload[];
struct ipw_error_elem elem[];
} __packed;
#ifdef CONFIG_IPW2200_PROMISCUOUS