From: Philippe Mathieu-Daudé Date: Fri, 11 Aug 2023 17:47:50 +0000 (+0100) Subject: hw/nvme: Use #define to avoid variable length array X-Git-Tag: v8.2.0-rc0~128^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b02c2a85a6c8e5ecc1bfca1ef794b5897c9ebad3;p=thirdparty%2Fqemu.git hw/nvme: Use #define to avoid variable length array In nvme_map_sgl() we create an array segment[] whose size is the 'const int SEG_CHUNK_SIZE'. Since this is C, rather than C++, a "const int foo" is not a true constant, it's merely a variable with a constant value, and so semantically segment[] is a variable-length array. Switch SEG_CHUNK_SIZE to a #define so that we can make the segment[] array truly fixed-size, in the sense that it doesn't trigger the -Wvla warning. The codebase has very few VLAs, and if we can get rid of them all we can make the compiler error on new additions. This is a defensive measure against security bugs where an on-stack dynamic allocation isn't correctly size-checked (e.g. CVE-2021-3527). [PMM: rebased (function has moved file), expand commit message based on discussion from previous version of patch] Signed-off-by: Philippe Mathieu-Daudé Signed-off-by: Peter Maydell Signed-off-by: Klaus Jensen --- diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c index 539d2735531..d99a6f5c9a2 100644 --- a/hw/nvme/ctrl.c +++ b/hw/nvme/ctrl.c @@ -1045,7 +1045,7 @@ static uint16_t nvme_map_sgl(NvmeCtrl *n, NvmeSg *sg, NvmeSglDescriptor sgl, * descriptors and segment chain) than the command transfer size, so it is * not bounded by MDTS. */ - const int SEG_CHUNK_SIZE = 256; +#define SEG_CHUNK_SIZE 256 NvmeSglDescriptor segment[SEG_CHUNK_SIZE], *sgld, *last_sgld; uint64_t nsgld;