From c576eddf1ce820568da973d8a383073443355fe7 Mon Sep 17 00:00:00 2001 From: Tianlin Li Date: Tue, 17 Dec 2019 13:45:28 -0600 Subject: drivers/misc: sram-exec: have the callers of set_memory_*() check the return value Right now several architectures allow their set_memory_*() family of functions to fail, but callers may not be checking the return values. If set_memory_*() returns with an error, call-site assumptions may be infact wrong to assume that it would either succeed or not succeed at all. Ideally, the failure of set_memory_*() should be passed up the call stack, and callers should examine the failure and deal with it. Need to fix the callers and add the __must_check attribute. They also may not provide any level of atomicity, in the sense that the memory protections may be left incomplete on failure. This issue likely has a few steps on effects architectures: 1) Have all callers of set_memory_*() helpers check the return value. 2) Add __must_check to all set_memory_*() helpers so that new uses do not ignore the return value. 3) Add atomicity to the calls so that the memory protections aren't left in a partial state. This series is part of step 1. Make sram driver check the return value of set_memory_*(). Signed-off-by: Tianlin Li Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20191217194528.16461-1-tli@digitalocean.com Signed-off-by: Greg Kroah-Hartman --- drivers/misc/sram-exec.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/drivers/misc/sram-exec.c b/drivers/misc/sram-exec.c index d054e2842a5f..cb57ac6ab4c3 100644 --- a/drivers/misc/sram-exec.c +++ b/drivers/misc/sram-exec.c @@ -85,6 +85,7 @@ void *sram_exec_copy(struct gen_pool *pool, void *dst, void *src, unsigned long base; int pages; void *dst_cpy; + int ret; mutex_lock(&exec_pool_list_mutex); list_for_each_entry(p, &exec_pool_list, list) { @@ -104,16 +105,28 @@ void *sram_exec_copy(struct gen_pool *pool, void *dst, void *src, mutex_lock(&part->lock); - set_memory_nx((unsigned long)base, pages); - set_memory_rw((unsigned long)base, pages); + ret = set_memory_nx((unsigned long)base, pages); + if (ret) + goto error_out; + ret = set_memory_rw((unsigned long)base, pages); + if (ret) + goto error_out; dst_cpy = fncpy(dst, src, size); - set_memory_ro((unsigned long)base, pages); - set_memory_x((unsigned long)base, pages); + ret = set_memory_ro((unsigned long)base, pages); + if (ret) + goto error_out; + ret = set_memory_x((unsigned long)base, pages); + if (ret) + goto error_out; mutex_unlock(&part->lock); return dst_cpy; + +error_out: + mutex_unlock(&part->lock); + return NULL; } EXPORT_SYMBOL_GPL(sram_exec_copy); -- cgit v1.2.3