5.4-stable review patch. If anyone has any objections, please let me know.
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From: Stuart Hayes stuart.w.hayes@gmail.com
[ Upstream commit f4b0fa38d5fefe9aed6ed831f3bd3538c168ee19 ]
The dell_rbu driver will use memset() to clear the data held by each packet when it is no longer needed (when the driver is unloaded, the packet size is changed, etc).
The amount of memory that is cleared (before this patch) is the normal packet size. However, the last packet in the list may be smaller.
Fix this to only clear the memory actually used by each packet, to prevent it from writing past the end of data buffer.
Because the packet data buffers are allocated with __get_free_pages() (in page-sized increments), this bug could only result in a buffer being overwritten when a packet size larger than one page is used. The only user of the dell_rbu module should be the Dell BIOS update program, which uses a packet size of 4096, so no issues should be seen without the patch, it just blocks the possiblity.
Fixes: 6c54c28e69f2 ("[PATCH] dell_rbu: new Dell BIOS update driver") Signed-off-by: Stuart Hayes stuart.w.hayes@gmail.com Link: https://lore.kernel.org/r/20250609184659.7210-5-stuart.w.hayes@gmail.com Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Signed-off-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/platform/x86/dell_rbu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/platform/x86/dell_rbu.c b/drivers/platform/x86/dell_rbu.c index 3691391fea6b1..16e4614ad3e47 100644 --- a/drivers/platform/x86/dell_rbu.c +++ b/drivers/platform/x86/dell_rbu.c @@ -344,7 +344,7 @@ static void packet_empty_list(void) * zero out the RBU packet memory before freeing * to make sure there are no stale RBU packets left in memory */ - memset(newpacket->data, 0, rbu_data.packetsize); + memset(newpacket->data, 0, newpacket->length); set_memory_wb((unsigned long)newpacket->data, 1 << newpacket->ordernum); free_pages((unsigned long) newpacket->data,