diff options
| author | Sergey Shtylyov <s.shtylyov@omp.ru> | 2022-03-31 00:09:07 +0300 |
|---|---|---|
| committer | Ulf Hansson <ulf.hansson@linaro.org> | 2022-04-26 14:05:19 +0200 |
| commit | 103da0667d4b7cdbc667666bd0e64899f3801033 (patch) | |
| tree | 7a430f2e522bd8d535eea133880929e7be0abe48 /drivers/mmc/core/block.c | |
| parent | 7792fdf626c20aa4e0d2b0daacf4e30df3ff9583 (diff) | |
mmc: core: block: fix sloppy typing in mmc_blk_ioctl_multi_cmd()
Despite mmc_ioc_multi_cmd::num_of_cmds is a 64-bit field, its maximum
value is limited to MMC_IOC_MAX_CMDS (only 255); using a 64-bit local
variable to hold a copy of that field leads to gcc generating ineffective
loop code: despite the source code using an *int* variable for the loop
counters, the 32-bit object code uses 64-bit unsigned counters. Also,
gcc has to drop the most significant word of that 64-bit variable when
calling kcalloc() and assigning to mmc_queue_req::ioc_count anyway.
Using the *unsigned int* variable instead results in a better code.
Found by Linux Verification Center (linuxtesting.org) with the SVACE static
analysis tool.
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Link: https://lore.kernel.org/r/eea3b0bd-6091-f005-7189-b5b7868abdb6@omp.ru
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/mmc/core/block.c')
| -rw-r--r-- | drivers/mmc/core/block.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c index 506dc900f5c7..b35e7a95798b 100644 --- a/drivers/mmc/core/block.c +++ b/drivers/mmc/core/block.c @@ -676,8 +676,9 @@ static int mmc_blk_ioctl_multi_cmd(struct mmc_blk_data *md, struct mmc_ioc_cmd __user *cmds = user->cmds; struct mmc_card *card; struct mmc_queue *mq; - int i, err = 0, ioc_err = 0; + int err = 0, ioc_err = 0; __u64 num_of_cmds; + unsigned int i, n; struct request *req; if (copy_from_user(&num_of_cmds, &user->num_of_cmds, @@ -690,15 +691,16 @@ static int mmc_blk_ioctl_multi_cmd(struct mmc_blk_data *md, if (num_of_cmds > MMC_IOC_MAX_CMDS) return -EINVAL; - idata = kcalloc(num_of_cmds, sizeof(*idata), GFP_KERNEL); + n = num_of_cmds; + idata = kcalloc(n, sizeof(*idata), GFP_KERNEL); if (!idata) return -ENOMEM; - for (i = 0; i < num_of_cmds; i++) { + for (i = 0; i < n; i++) { idata[i] = mmc_blk_ioctl_copy_from_user(&cmds[i]); if (IS_ERR(idata[i])) { err = PTR_ERR(idata[i]); - num_of_cmds = i; + n = i; goto cmd_err; } /* This will be NULL on non-RPMB ioctl():s */ @@ -725,18 +727,18 @@ static int mmc_blk_ioctl_multi_cmd(struct mmc_blk_data *md, req_to_mmc_queue_req(req)->drv_op = rpmb ? MMC_DRV_OP_IOCTL_RPMB : MMC_DRV_OP_IOCTL; req_to_mmc_queue_req(req)->drv_op_data = idata; - req_to_mmc_queue_req(req)->ioc_count = num_of_cmds; + req_to_mmc_queue_req(req)->ioc_count = n; blk_execute_rq(req, false); ioc_err = req_to_mmc_queue_req(req)->drv_op_result; /* copy to user if data and response */ - for (i = 0; i < num_of_cmds && !err; i++) + for (i = 0; i < n && !err; i++) err = mmc_blk_ioctl_copy_to_user(&cmds[i], idata[i]); blk_mq_free_request(req); cmd_err: - for (i = 0; i < num_of_cmds; i++) { + for (i = 0; i < n; i++) { kfree(idata[i]->buf); kfree(idata[i]); } |