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greybus: enforce max representable message size

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We represent the size of a message using a 16-bit field.  It's
possible for a host driver to advertise a maximum message size
that's bigger than that.  If that happens, reduce the host device's
maximum buffer size to the maximum we can represent the first time
a message is allocated.

This information is actually only used by the Greybus code, but
because we're modifying a value that's "owned" by the host driver,
issue a warning when this limit is being imposed

Ensure (at build time) that our own definition is sane as well.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
This commit is contained in:
Alex Elder
2014-12-01 07:53:07 -06:00
committed by Greg Kroah-Hartman
parent 94b15d7613
commit ab3cf8dc7d
1 changed files with 9 additions and 0 deletions
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9
drivers/staging/greybus/operation.c
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@@ -299,6 +299,12 @@ gb_operation_message_alloc(struct greybus_host_device *hd, u8 type,
size_t size;
u8 *buffer;
if (hd->buffer_size_max > GB_OPERATION_MESSAGE_SIZE_MAX) {
pr_warn("limiting buffer size to %u\n",
GB_OPERATION_MESSAGE_SIZE_MAX);
hd->buffer_size_max = GB_OPERATION_MESSAGE_SIZE_MAX;
}
if (message_size > hd->buffer_size_max)
return NULL;
@@ -750,6 +756,9 @@ int gb_operation_sync(struct gb_connection *connection, int type,
int gb_operation_init(void)
{
BUILD_BUG_ON(GB_OPERATION_MESSAGE_SIZE_MAX >
U16_MAX - sizeof(struct gb_operation_msg_hdr));
gb_operation_cache = kmem_cache_create("gb_operation_cache",
sizeof(struct gb_operation), 0, 0, NULL);
if (!gb_operation_cache)