Avoid segfault when user-specified initrd is a symlink to /dev/null #261
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We check for a microcode update initrd, so we can early-load it, by comparing the resolved file names to the ending "-ucode.cpio". In the case that a user has explicitly masked an initrd by symlinking a name in /etc/kernel/initrd.d/ to /dev/null, we store NULL in the resolved filename pointer. Before we do the actual comparison, we do a strlen to make sure the filename is longer than the desired match. For a NULL pointer, that results in a segfault, so for that case, explicitly code the length to 0 instead of calling strlen on it. Signature: [277506.631610] clr-boot-manage[2369580]: segfault at 0 ip 0000558974796218 sp 00007ffca90d9658 error 4 cpu 18 in libc-2.40.so[196218,558974628000+184000] likely on CPU 18 (core 8, socket 0) [277506.631627] Code: 0f 84 5e fd ff ff 48 89 f8 0f bc c9 f3 a4 c3 0f 1f 00 89 f8 62 a1 fd 00 ef c0 25 ff 0f 00 00 3d e0 0f 00 00 0f 87 28 01 00 00 <62> f1 7d 20 74 07 c5 fb 93 c0 85 c0 74 1a 0f bc c0 c3 66 0f 1f 44 $ sudo CBM_DEBUG=1 clr-boot-manager update [DEBUG] cbm (../src/cli/cli.c:L142): No such file: //etc/kernel/update_efi_vars [INFO] cbm (../src/bootman/bootman.c:L788): Current running kernel: 6.10.12-1467.native [INFO] cbm (../src/bootman/sysconfig.c:L179): Discovered UEFI ESP: /dev/disk/by-partuuid/cb7f514a-2dd7-445d-9dec-2d5d105c6eee [INFO] cbm (../src/bootman/sysconfig.c:L256): Fully resolved boot device: /dev/sda1 [DEBUG] cbm (../src/bootman/bootman.c:L141): shim-systemd caps: 0x26, wanted: 0x26 [DEBUG] cbm (../src/bootman/bootman.c:L156): UEFI boot now selected (shim-systemd) [DEBUG] cbm (../src/bootman/bootman.c:L829): Non regular file: ///etc/kernel/initrd.d/.., skipping. Segmentation fault (gdb) bt #0 0x0000555555396218 in __strlen_evex () from /usr/lib64/libc.so.6 clearlinux#1 0x000055555555b9cc in _boot_manager_enumerate_initrds_freestanding () at ../src/bootman/bootman.c:889 clearlinux#2 0x000055555555d570 in boot_manager_enumerate_initrds_freestanding () at ../src/bootman/bootman.c:918 clearlinux#3 0x000055555555b170 in cbm_command_update_do () at ../src/cli/ops/update.c:82 clearlinux#4 0x000055555555b2ac in cbm_command_update () at ../src/cli/ops/update.c:44 clearlinux#5 0x000055555555990b in main () at ../src/cli/main.c:296
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bryteise
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Oct 11, 2024
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Related to clearlinux/distribution#3192 |
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We check for a microcode update initrd, so we can early-load it, by comparing the resolved file names to the ending "-ucode.cpio". In the case that a user has explicitly masked an initrd by symlinking a name in /etc/kernel/initrd.d/ to /dev/null, we store NULL in the resolved filename pointer.
Before we do the actual comparison, we do a strlen to make sure the filename is longer than the desired match. For a NULL pointer, that results in a segfault, so for that case, explicitly code the length to 0 instead of calling strlen on it.
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