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In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu: Fix buffer size in gfx_v9_4_3_init_ cp_compute_microcode() and rlc_microcode() The function gfx_v9_4_3_init_microcode in gfx_v9_4_3.c was generating about potential truncation of output when using the snprintf function. The issue was due to the size of the buffer 'ucode_prefix' being too small to accommodate the maximum possible length of the string being written into it. The string being written is "amdgpu/%s_mec.bin" or "amdgpu/%s_rlc.bin", where %s is replaced by the value of 'chip_name'. The length of this string without the %s is 16 characters. The warning message indicated that 'chip_name' could be up to 29 characters long, resulting in a total of 45 characters, which exceeds the buffer size of 30 characters. To resolve this issue, the size of the 'ucode_prefix' buffer has been reduced from 30 to 15. This ensures that the maximum possible length of the string being written into the buffer will not exceed its size, thus preventing potential buffer overflow and truncation issues. Fixes the below with gcc W=1: drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c: In function âgfx_v9_4_3_early_initâ: drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c:379:52: warning: â%sâ directive output may be truncated writing up to 29 bytes into a region of size 23 [-Wformat-truncation=] 379 | snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_rlc.bin", chip_name); | ^~ ...... 439 | r = gfx_v9_4_3_init_rlc_microcode(adev, ucode_prefix); | ~~~~~~~~~~~~ drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c:379:9: note: âsnprintfâ output between 16 and 45 bytes into a destination of size 30 379 | snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_rlc.bin", chip_name); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c:413:52: warning: â%sâ directive output may be truncated writing up to 29 bytes into a region of size 23 [-Wformat-truncation=] 413 | snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mec.bin", chip_name); | ^~ ...... 443 | r = gfx_v9_4_3_init_cp_compute_microcode(adev, ucode_prefix); | ~~~~~~~~~~~~ drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c:413:9: note: âsnprintfâ output between 16 and 45 bytes into a destination of size 30 413 | snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mec.bin", chip_name); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CVSS 3.1 Base Score 7.8. CVSS Attack Vector: local. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).
The following code asks the user to enter their last name and then attempts to store the value entered in the last_name array.
scanf ("%s", last_name);The problem with the code above is that it does not restrict or limit the size of the name entered by the user. If the user enters "Very_very_long_last_name" which is 24 characters long, then a buffer overflow will occur since the array can only hold 20 characters total.
The following code attempts to create a local copy of a buffer to perform some manipulations to the data.
}...However, the programmer does not ensure that the size of the data pointed to by string will fit in the local buffer and blindly copies the data with the potentially dangerous strcpy() function. This may result in a buffer overflow condition if an attacker can influence the contents of the string parameter.
The excerpt below calls the gets() function in C, which is inherently unsafe.
}...However, the programmer uses the function gets() which is inherently unsafe because it blindly copies all input from STDIN to the buffer without restricting how much is copied. This allows the user to provide a string that is larger than the buffer size, resulting in an overflow condition.
In the following example, a server accepts connections from a client and processes the client request. After accepting a client connection, the program will obtain client information using the gethostbyaddr method, copy the hostname of the client that connected to a local variable and output the hostname of the client to a log file.
...
close(serversocket);
}
close(clientsocket);However, the hostname of the client that connected may be longer than the allocated size for the local hostname variable. This will result in a buffer overflow when copying the client hostname to the local variable using the strcpy method.
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