On 3/21/2024 11:16 AM, Srinivasan Shanmugam wrote: > The snprintf function is used to write a formatted string into fw_name. > The format of the string is "amdgpu/%s_mes%s.bin", where %s is replaced > by the string in ucode_prefix and the second %s is replaced by either > "_2" or "1" depending on the condition pipe == AMDGPU_MES_SCHED_PIPE. > > The length of the string "amdgpu/%s_mes%s.bin" is 16 characters plus the > length of ucode_prefix and the length of the string "_2" or "1". The > size of ucode_prefix is 30, so the maximum length of ucode_prefix is 29 > characters (since one character is needed for the null terminator). > Therefore, the maximum possible length of the string written into > fw_name is 16 + 29 + 2 = 47 characters. > > The size of fw_name is 40, so if the length of the string written into > fw_name is more than 39 characters (since one character is needed for > the null terminator), it will be truncated by the snprintf function, and > thus warnings will be seen. > > By increasing the size of fw_name to 50, we ensure that fw_name is > large enough to hold the maximum possible length of the string, so the > snprintf function will not truncate the output. > > Fixes the below with gcc W=1: > drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c: In function ‘amdgpu_mes_init_microcode’: > drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c:1482:66: warning: ‘%s’ directive output may be truncated writing up to 1 bytes into a region of size between 0 and 29 [-Wformat-truncation=] > 1482 | snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mes%s.bin", > | ^~ > drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c:1482:17: note: ‘snprintf’ output between 16 and 46 bytes into a destination of size 40 > 1482 | snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mes%s.bin", > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > 1483 | ucode_prefix, > | ~~~~~~~~~~~~~ > 1484 | pipe == AMDGPU_MES_SCHED_PIPE ? "" : "1"); > | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c:1477:66: warning: ‘%s’ directive output may be truncated writing 1 byte into a region of size between 0 and 29 [-Wformat-truncation=] > 1477 | snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mes%s.bin", > | ^~ > 1478 | ucode_prefix, > 1479 | pipe == AMDGPU_MES_SCHED_PIPE ? "_2" : "1"); > | ~~~ > drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c:1477:17: note: ‘snprintf’ output between 17 and 46 bytes into a destination of size 40 > 1477 | snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mes%s.bin", > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > 1478 | ucode_prefix, > | ~~~~~~~~~~~~~ > 1479 | pipe == AMDGPU_MES_SCHED_PIPE ? "_2" : "1"); > | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c:1477:66: warning: ‘%s’ directive output may be truncated writing 2 bytes into a region of size between 0 and 29 [-Wformat-truncation=] > 1477 | snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mes%s.bin", > | ^~ > 1478 | ucode_prefix, > 1479 | pipe == AMDGPU_MES_SCHED_PIPE ? "_2" : "1"); > | ~~~~ > drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c:1477:17: note: ‘snprintf’ output between 18 and 47 bytes into a destination of size 40 > 1477 | snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mes%s.bin", > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > 1478 | ucode_prefix, > | ~~~~~~~~~~~~~ > 1479 | pipe == AMDGPU_MES_SCHED_PIPE ? "_2" : "1"); > | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c:1489:62: warning: ‘_mes.bin’ directive output may be truncated writing 8 bytes into a region of size between 4 and 33 [-Wformat-truncation=] > 1489 | snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mes.bin", > | ^~~~~~~~ > drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c:1489:17: note: ‘snprintf’ output between 16 and 45 bytes into a destination of size 40 > 1489 | snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mes.bin", > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > 1490 | ucode_prefix); > | ~~~~~~~~~~~~~ > > Cc: Alex Deucher <alexander.deucher@xxxxxxx> > Cc: Christian König <christian.koenig@xxxxxxx> > Suggested-by: Lijo Lazar <lijo.lazar@xxxxxxx> > Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@xxxxxxx> Reviewed-by: Lijo Lazar <lijo.lazar@xxxxxxx> Thanks, Lijo > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c > index bc8906403270..78dfd027dc99 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c > @@ -1467,7 +1467,7 @@ int amdgpu_mes_init_microcode(struct amdgpu_device *adev, int pipe) > const struct mes_firmware_header_v1_0 *mes_hdr; > struct amdgpu_firmware_info *info; > char ucode_prefix[30]; > - char fw_name[40]; > + char fw_name[50]; > bool need_retry = false; > int r; >
