mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-06 10:58:48 +09:00
379d4ba831
Consider a program like below:
void prog(void)
{
{
struct bpf_dynptr ptr;
bpf_dynptr_from_mem(...);
}
...
{
struct bpf_dynptr ptr;
bpf_dynptr_from_mem(...);
}
}
Here, the C compiler based on lifetime rules in the C standard would be
well within in its rights to share stack storage for dynptr 'ptr' as
their lifetimes do not overlap in the two distinct scopes. Currently,
such an example would be rejected by the verifier, but this is too
strict. Instead, we should allow reinitializing over dynptr stack slots
and forget information about the old dynptr object.
The destroy_if_dynptr_stack_slot function already makes necessary checks
to avoid overwriting referenced dynptr slots. This is done to present a
better error message instead of forgetting dynptr information on stack
and preserving reference state, leading to an inevitable but
undecipherable error at the end about an unreleased reference which has
to be associated back to its allocating call instruction to make any
sense to the user.
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230121002241.2113993-6-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.