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Kernel+LibC+LibELF: Set stack size based on PT_GNU_STACK during execve

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Some programs explicitly ask for a different initial stack size than
what the OS provides. This is implemented in ELF by having a
PT_GNU_STACK header which has its p_memsz set to the amount that the
program requires. This commit implements this policy by reading the
p_memsz of the header and setting the main thread stack size to that.
ELF::Image::validate_program_headers ensures that the size attribute is
a reasonable value.
This commit is contained in:
sin-ack 2022-10-01 19:29:59 +00:00 • committed by Andrew Kaster
parent 3275015786
commit ef6921d7c7
9 changed files with 43 additions and 7 deletions
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16
Userland/Libraries/LibELF/Validation.cpp
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@ -7,6 +7,7 @@
#include <AK/Assertions.h>
#include <AK/Checked.h>
#include <Kernel/API/serenity_limits.h>
#include <LibC/elf.h>
#include <LibELF/Validation.h>
#include <limits.h>
@ -298,6 +299,21 @@ ErrorOr<bool> validate_program_headers(ElfW(Ehdr) const& elf_header, size_t file
if (verbose)
dbgln("Possible shenanigans! Validating an ELF with executable stack.");
}
if (program_header.p_memsz != 0) {
if (program_header.p_memsz < static_cast<unsigned>(PTHREAD_STACK_MIN) || program_header.p_memsz > static_cast<unsigned>(PTHREAD_STACK_MAX)) {
if (verbose)
dbgln("PT_GNU_STACK defines an unacceptable stack size.");
return false;
}
if (program_header.p_memsz % PAGE_SIZE != 0) {
if (verbose)
dbgln("PT_GNU_STACK size is not page-aligned.");
return false;
}
}
break;
case PT_GNU_RELRO:
if ((program_header.p_flags & PF_X) && (program_header.p_flags & PF_W)) {