From: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> 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@xxxxxxxxxxxxxxx Reported-by: kernel test robot <lkp@xxxxxxxxx> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> Link: https://lore.kernel.org/linux-hardening/20210420001631.GA45456@embeddedor/ Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 {
