From 4318432ccd3f7fb69b7169f39dcae3d4ee04f5ea Mon Sep 17 00:00:00 2001 From: Laszlo Ersek Date: Wed, 16 Sep 2020 17:15:10 +0200 Subject: [PATCH] hw/nvram/fw_cfg: fix FWCfgDataGeneratorClass::get_data() consumption MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The documentation on g_byte_array_free() says: > Returns > > the element data if free_segment is FALSE, otherwise NULL. The element > data should be freed using g_free(). Because we currently call g_byte_array_free() with free_segment=TRUE, we end up passing data=NULL to fw_cfg_add_file(). On the plus side, fw_cfg_data_read() and fw_cfg_dma_transfer() both deal with NULL data gracefully: QEMU does not crash when the guest reads such an item, the guest just gets a properly sized, but zero-filled blob. However, the bug breaks UEFI HTTPS boot, as the IANA_TLS_CIPHER array, generated otherwise correctly by the "tls-cipher-suites" object, is in effect replaced with a zero blob. Fix the issue by passing free_segment=FALSE to g_byte_array_free(): - the caller (fw_cfg_add_from_generator()) temporarily assumes ownership of the generated byte array, - then ownership of the byte array is transfered to fw_cfg, as fw_cfg_add_file() links (not copies) "data" into fw_cfg. Cc: "Daniel P. Berrangé" Cc: "Philippe Mathieu-Daudé" Cc: Gerd Hoffmann Fixes: 3203148917d035b09f71986ac2eaa19a352d6d9d Signed-off-by: Laszlo Ersek Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Daniel P. Berrangé Message-Id: <20200916151510.22767-1-lersek@redhat.com> Signed-off-by: Philippe Mathieu-Daudé --- hw/nvram/fw_cfg.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c index f3a4728288..0e95d057fd 100644 --- a/hw/nvram/fw_cfg.c +++ b/hw/nvram/fw_cfg.c @@ -1056,7 +1056,7 @@ bool fw_cfg_add_from_generator(FWCfgState *s, const char *filename, return false; } size = array->len; - fw_cfg_add_file(s, filename, g_byte_array_free(array, TRUE), size); + fw_cfg_add_file(s, filename, g_byte_array_free(array, FALSE), size); return true; }