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fallback: find_boot_options(): make the allocation path prettier.

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Covscan believes all this stuff:

 852                bs = 0;
 853                rc = uefi_call_wrapper(fh2->Read, 3, fh2, &bs, NULL);
    7. Condition rc == (9223372036854775813UL /* 0x8000000000000000UL | 5 */), taking false branch.
    8. Condition rc == 0, taking false branch.
    15. Condition rc == (9223372036854775813UL /* 0x8000000000000000UL | 5 */), taking false branch.
    16. Condition rc == 0, taking true branch.
    17. Condition bs != 0, taking true branch.
    30. Condition rc == (9223372036854775813UL /* 0x8000000000000000UL | 5 */), taking false branch.
    31. Condition rc == 0, taking false branch.
 854                if (rc == EFI_BUFFER_TOO_SMALL ||
 855                                (rc == EFI_SUCCESS && bs != 0)) {
 856                        buffer = AllocateZeroPool(bs);
    18. Condition !buffer, taking false branch.
 857                        if (!buffer) {
 858                                Print(L"Could not allocate memory\n");
 859                                /* sure, this might work, why not? */
 860                                uefi_call_wrapper(fh2->Close, 1, fh2);
 861                                uefi_call_wrapper(fh->Close, 1, fh);
 862                                return EFI_OUT_OF_RESOURCES;
 863                        }
 864
 865                        rc = uefi_call_wrapper(fh2->Read, 3, fh2, &bs, buffer);
 866                }
    9. Condition bs == 0, taking false branch.
    19. Condition bs == 0, taking false branch.
    32. Condition bs == 0, taking false branch.
 867                if (bs == 0)
 868                        break;
 869
    10. Condition (INTN)rc < 0, taking false branch.
    20. Condition (INTN)rc < 0, taking false branch.
    33. Condition (INTN)rc < 0, taking false branch.
 870                if (EFI_ERROR(rc)) {
 871                        Print(L"Could not read \\EFI\\: %d\n", rc);
 872                        if (buffer) {
 873                                FreePool(buffer);
 874                                buffer = NULL;
 875                        }
 876                        uefi_call_wrapper(fh2->Close, 1, fh2);
 877                        uefi_call_wrapper(fh->Close, 1, fh);
 878                        return rc;
 879                }
    34. alias_transfer: Assigning: fi = buffer.
 880                EFI_FILE_INFO *fi = buffer;
 881
    11. Condition !(fi->Attribute & 16), taking false branch.
    21. Condition !(fi->Attribute & 16), taking false branch.
    CID 182858 (#1-3 of 3): Explicit null dereferenced (FORWARD_NULL)35. var_deref_op: Dereferencing null pointer fi.
 882                if (!(fi->Attribute & EFI_FILE_DIRECTORY)) {
 883                        FreePool(buffer);
 884                        buffer = NULL;
 885                        continue;
 886                }

Because it doesn't know that when bs==0, fh2->Read() will return
EFI_BUFFER_TOO_SMALL and set bs to the size we need to allocate, so the
allocation path is always taken.  Instead, handle our exit/error paths
directly there, and make the allocation path nonconditional.

Signed-off-by: Peter Jones <pjones@redhat.com>
This commit is contained in:
Peter Jones 2017-09-27 16:13:57 -04:00 committed by Peter Jones
parent 111f82f2f6
commit 89126c1ab5
1 changed files with 13 additions and 13 deletions
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26
fallback.c
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@ -850,24 +850,24 @@ find_boot_options(EFI_HANDLE device)
do {
bs = 0;
rc = uefi_call_wrapper(fh2->Read, 3, fh2, &bs, NULL);
if (rc == EFI_BUFFER_TOO_SMALL ||
(rc == EFI_SUCCESS && bs != 0)) {
buffer = AllocateZeroPool(bs);
if (!buffer) {
Print(L"Could not allocate memory\n");
/* sure, this might work, why not? */
uefi_call_wrapper(fh2->Close, 1, fh2);
uefi_call_wrapper(fh->Close, 1, fh);
return EFI_OUT_OF_RESOURCES;
}
rc = uefi_call_wrapper(fh2->Read, 3, fh2, &bs, buffer);
if (EFI_ERROR(rc) && rc != EFI_BUFFER_TOO_SMALL) {
Print(L"Could not read \\EFI\\: %d\n", rc);
return rc;
}
if (bs == 0)
break;
buffer = AllocateZeroPool(bs);
if (!buffer) {
Print(L"Could not allocate memory\n");
/* sure, this might work, why not? */
uefi_call_wrapper(fh2->Close, 1, fh2);
uefi_call_wrapper(fh->Close, 1, fh);
return EFI_OUT_OF_RESOURCES;
}
rc = uefi_call_wrapper(fh2->Read, 3, fh2, &bs, buffer);
if (EFI_ERROR(rc)) {
Print(L"Could not read \\EFI\\: %d\n", rc);
if (buffer) {
FreePool(buffer);
buffer = NULL;