From: Gustavo A. R. Silva gustavoars@kernel.org
commit 8d4abca95ecc82fc8c41912fa0085281f19cc29f upstream.
Fix an 11-year old bug in ngene_command_config_free_buf() while addressing the following warnings caught with -Warray-bounds:
arch/alpha/include/asm/string.h:22:16: warning: '__builtin_memcpy' offset [12, 16] from the object at 'com' is out of the bounds of referenced subobject 'config' with type 'unsigned char' at offset 10 [-Warray-bounds] arch/x86/include/asm/string_32.h:182:25: warning: '__builtin_memcpy' offset [12, 16] from the object at 'com' is out of the bounds of referenced subobject 'config' with type 'unsigned char' at offset 10 [-Warray-bounds]
The problem is that the original code is trying to copy 6 bytes of data into a one-byte size member _config_ of the wrong structue FW_CONFIGURE_BUFFERS, in a single call to memcpy(). This causes a legitimate compiler warning because memcpy() overruns the length of &com.cmd.ConfigureBuffers.config. It seems that the right structure is FW_CONFIGURE_FREE_BUFFERS, instead, because it contains 6 more members apart from the header _hdr_. Also, the name of the function ngene_command_config_free_buf() suggests that the actual intention is to ConfigureFreeBuffers, instead of ConfigureBuffers (which takes place in the function ngene_command_config_buf(), above).
Fix this by enclosing those 6 members of struct FW_CONFIGURE_FREE_BUFFERS into new struct config, and use &com.cmd.ConfigureFreeBuffers.config as the destination address, instead of &com.cmd.ConfigureBuffers.config, when calling memcpy().
This also helps with the ongoing efforts to globally enable -Warray-bounds and get us closer to being able to tighten the FORTIFY_SOURCE routines on memcpy().
Link: https://github.com/KSPP/linux/issues/109 Fixes: dae52d009fc9 ("V4L/DVB: ngene: Initial check-in") Cc: stable@vger.kernel.org Reported-by: kernel test robot lkp@intel.com Reviewed-by: Kees Cook keescook@chromium.org Signed-off-by: Gustavo A. R. Silva gustavoars@kernel.org Link: https://lore.kernel.org/linux-hardening/20210420001631.GA45456@embeddedor/ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/media/pci/ngene/ngene-core.c | 2 +- drivers/media/pci/ngene/ngene.h | 14 ++++++++------ 2 files changed, 9 insertions(+), 7 deletions(-)
--- a/drivers/media/pci/ngene/ngene-core.c +++ b/drivers/media/pci/ngene/ngene-core.c @@ -402,7 +402,7 @@ static int ngene_command_config_free_buf
com.cmd.hdr.Opcode = CMD_CONFIGURE_FREE_BUFFER; com.cmd.hdr.Length = 6; - memcpy(&com.cmd.ConfigureBuffers.config, config, 6); + memcpy(&com.cmd.ConfigureFreeBuffers.config, config, 6); com.in_len = 6; com.out_len = 0;
--- a/drivers/media/pci/ngene/ngene.h +++ b/drivers/media/pci/ngene/ngene.h @@ -407,12 +407,14 @@ enum _BUFFER_CONFIGS {
struct FW_CONFIGURE_FREE_BUFFERS { struct FW_HEADER hdr; - u8 UVI1_BufferLength; - u8 UVI2_BufferLength; - u8 TVO_BufferLength; - u8 AUD1_BufferLength; - u8 AUD2_BufferLength; - u8 TVA_BufferLength; + struct { + u8 UVI1_BufferLength; + u8 UVI2_BufferLength; + u8 TVO_BufferLength; + u8 AUD1_BufferLength; + u8 AUD2_BufferLength; + u8 TVA_BufferLength; + } __packed config; } __attribute__ ((__packed__));
struct FW_CONFIGURE_UART {