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Subject[PATCH 21/26] cciss: sanitize max commands
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Date
From: Stephen M. Cameron <scameron@beardog.cce.hp.com>

cciss: sanitize max commands
Some controllers might try to tell us they support 0 commands
in performant mode. This is a lie told by buggy firmware.
We have to be wary of this lest we try to allocate a negative
number of command blocks, which will be treated as unsigned,
and get an out of memory condition.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
---
drivers/block/cciss.c | 14 +++++++++++++-
1 files changed, 13 insertions(+), 1 deletions(-)
diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index b3060ec..6d4c4f2 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -4112,13 +4112,25 @@ static int __devinit cciss_find_cfgtables(ctlr_info_t *h)
return 0;
}

+static void __devinit cciss_get_max_perf_mode_cmds(struct ctlr_info *h)
+{
+ h->max_commands = readl(&(h->cfgtable->MaxPerformantModeCommands));
+ if (h->max_commands < 16) {
+ dev_warn(&h->pdev->dev, "Controller reports "
+ "max supported commands of %d, an obvious lie. "
+ "Using 16. Ensure that firmware is up to date.\n",
+ h->max_commands);
+ h->max_commands = 16;
+ }
+}
+
/* Interrogate the hardware for some limits:
* max commands, max SG elements without chaining, and with chaining,
* SG chain block size, etc.
*/
static void __devinit cciss_find_board_params(ctlr_info_t *h)
{
- h->max_commands = readl(&(h->cfgtable->MaxPerformantModeCommands));
+ cciss_get_max_perf_mode_cmds(h);
h->nr_cmds = h->max_commands - 4; /* Allow room for some ioctls */
h->maxsgentries = readl(&(h->cfgtable->MaxSGElements));
/*


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