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elfdump: handle small files more gracefully

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elfdump -E on an empty file would complain "Invalid argument" because
it tried to mmap zero bytes.  With the -E flag, elfdump should
simply exit non-zero.  For tiny files, the code would reference off
the end of the mapped region.

Ensure the file is large enough to contain an ELF header before mapping it.

MFC after:	1 week
Sponsored by:	Dell EMC Isilon
This commit is contained in:
Eric van Gyzen 2022-02-17 09:53:48 -06:00
parent 95edb10b47
commit 86e5e10daf
1 changed files with 6 additions and 1 deletions
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7
usr.bin/elfdump/elfdump.c
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@ -585,6 +585,11 @@ main(int ac, char **av)
if ((fd = open(*av, O_RDONLY)) < 0 ||
fstat(fd, &sb) < 0)
err(1, "%s", *av);
if ((size_t)sb.st_size < sizeof(Elf32_Ehdr)) {
if (flags & ED_IS_ELF)
exit(1);
errx(1, "not an elf file");
}
cap_rights_init(&rights, CAP_MMAP_R);
if (caph_rights_limit(fd, &rights) < 0)
err(1, "unable to limit rights for %s", *av);
@ -598,7 +603,7 @@ main(int ac, char **av)
e = mmap(NULL, sb.st_size, PROT_READ, MAP_SHARED, fd, 0);
if (e == MAP_FAILED)
err(1, NULL);
if (!IS_ELF(*(Elf32_Ehdr *)e)) {
if (!IS_ELF(*e)) {
if (flags & ED_IS_ELF)
exit(1);
errx(1, "not an elf file");