mirror of
https://git.proxmox.com/git/efi-boot-shim
synced 2025-07-26 13:52:36 +00:00
a326513605
Covscan daftly claims:
288. var_compare_op: Comparing MokSB to null implies that MokSB might be null.
2330 if (MokSB) {
2331 menu_strings[i] = L"Change Secure Boot state";
2332 menu_item[i] = MOK_CHANGE_SB;
2333 i++;
2334 }
2335
...
2358 choice = console_select(perform_mok_mgmt, menu_strings, 0);
2359 if (choice < 0)
2360 goto out;
...
2362 switch (menu_item[choice]) {
...
2395 case MOK_CHANGE_SB:
CID 182841 (#1 of 1): Dereference after null check
(FORWARD_NULL)293. var_deref_model: Passing null pointer MokSB to
mok_sb_prompt, which dereferences it. [show details]
2396 efi_status = mok_sb_prompt(MokSB, MokSBSize);
Which is, of course, entirely false, beause for menu_item[choice] to be
MOK_CHANGE_SB, MokSB must be !NULL. And then:
252. Condition efi_status == 0, taking true branch.
2397 if (efi_status == EFI_SUCCESS)
2398 MokSB = NULL;
This guarantees it won't be in the list the next time through the loop.
This adds tests for NULLness before mok_sb_prompt(), just to make it
more clear to covscan what's going on.
Also do the same thing for all of:
MOK_CHANGE_SB
MOK_SET_PW
MOK_CHANGE_DB
MOK_ENROLL_MOKX
MOK_DELETE_MOKX
I also Lindent-ed everything I had to touch.
Three other minor errors are also fixed:
1) the loop in enter_mok_menu() leaked the menu allocations each time
through the loop
2) mok_sb_prompt(), mok_pw_prompt(), and mok_db_prompt() all call
FreePool() on their respective variables (MokSB, etc), and
check_mok_request() also calls FreePool() on these. This sounds
horrible, but it turns out it's not an issue, because they only free
them in their EFI_SUCCESS paths, and enter_mok_menu() resets the
system if any of the mok_XX_prompt() calls actually returned
EFI_SUCCESS, so we never get back to check_mok_request() for it to do
its FreePool() calls.
3) the loop in enter_mok_menu() winds up introducing a double free in
the call to free_menu(), but we also can't hit this bug, because all
the exit paths from the loop are "goto out" (or return error) rather
than actually exiting on the loop conditional.
Signed-off-by: Peter Jones <pjones@redhat.com>
|
||
|---|---|---|
| Cryptlib | ||
| include | ||
| lib | ||
| .gitignore | ||
| .syntastic_c_config | ||
| buildid.c | ||
| BUILDING | ||
| cert.S | ||
| COPYRIGHT | ||
| crypt_blowfish.c | ||
| elf_aarch64_efi.lds | ||
| elf_arm_efi.lds | ||
| elf_ia32_efi.lds | ||
| elf_ia64_efi.lds | ||
| elf_x86_64_efi.lds | ||
| errlog.c | ||
| fallback.c | ||
| httpboot.c | ||
| make-certs | ||
| Make.coverity | ||
| Make.defaults | ||
| Make.rules | ||
| Make.scan-build | ||
| Makefile | ||
| model.c | ||
| MokManager.c | ||
| MokVars.txt | ||
| netboot.c | ||
| PasswordCrypt.c | ||
| README | ||
| README.fallback | ||
| README.tpm | ||
| replacements.c | ||
| shim.c | ||
| shim.h | ||
| testplan.txt | ||
| TODO | ||
| tpm.c | ||
| version.c.in | ||
| version.h | ||
shim is a trivial EFI application that, when run, attempts to open and execute another application. It will initially attempt to do this via the standard EFI LoadImage() and StartImage() calls. If these fail (because secure boot is enabled and the binary is not signed with an appropriate key, for instance) it will then validate the binary against a built-in certificate. If this succeeds and if the binary or signing key are not blacklisted then shim will relocate and execute the binary. shim will also install a protocol which permits the second-stage bootloader to perform similar binary validation. This protocol has a GUID as described in the shim.h header file and provides a single entry point. On 64-bit systems this entry point expects to be called with SysV ABI rather than MSABI, and so calls to it should not be wrapped. On systems with a TPM chip enabled and supported by the system firmware, shim will extend various PCRs with the digests of the targets it is loading. A full list is in the file README.tpm . To use shim, simply place a DER-encoded public certificate in a file such as pub.cer and build with "make VENDOR_CERT_FILE=pub.cer". There are a couple of build options, and a couple of ways to customize the build, described in BUILDING.