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Kernel: Wrap much of sys$execve() in a block scope

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Since we don't return normally from this function, let's make it a
little extra difficult to accidentally leak something by leaving it on
the stack in this function.
This commit is contained in:
Andreas Kling 2022-01-13 23:17:52 +01:00
parent 0e72b04e7d
commit 0e08763483
1 changed files with 38 additions and 33 deletions
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9
Kernel/Syscalls/execve.cpp
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@ -838,8 +838,14 @@ ErrorOr<FlatPtr> Process::sys$execve(Userspace<const Syscall::SC_execve_params*>
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
TRY(require_promise(Pledge::exec));
Thread* new_main_thread = nullptr;
u32 prev_flags = 0;
// NOTE: Be extremely careful with allocating any kernel memory in this function.
// On success, the kernel stack will be lost.
// The explicit block scope below is specifically placed to minimize the number
// of stack locals in this function.
{
auto params = TRY(copy_typed_from_user(user_params));
if (params.arguments.length > ARG_MAX || params.environment.length > ARG_MAX)
@ -870,9 +876,8 @@ ErrorOr<FlatPtr> Process::sys$execve(Userspace<const Syscall::SC_execve_params*>
NonnullOwnPtrVector<KString> environment;
TRY(copy_user_strings(params.environment, environment));
Thread* new_main_thread = nullptr;
u32 prev_flags = 0;
TRY(exec(move(path), move(arguments), move(environment), new_main_thread, prev_flags));
}
// NOTE: If we're here, the exec has succeeded and we've got a new executable image!
// We will not return normally from this function. Instead, the next time we