Re: [PATCH 04/14] x86: use more conventional access_ok() definition
From: Al Viro <viro@zeniv.linux.org.uk>
Date: 2022-02-14 20:46:22
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On Mon, Feb 14, 2022 at 12:01:05PM -0800, Linus Torvalds wrote:
On Mon, Feb 14, 2022 at 11:46 AM Arnd Bergmann [off-list ref] wrote:quoted
As Al pointed out, they turned out to be necessary on sparc64, but the only definitions are on sparc64 and x86, so it's possible that they serve a similar purpose here, in which case changing the limit from TASK_SIZE to TASK_SIZE_MAX is probably wrong as well.x86-64 has always(*) used TASK_SIZE_MAX for access_ok(), and the get_user() assembler implementation does the same. I think any __range_not_ok() users that use TASK_SIZE are entirely historical, and should be just fixed.
IIRC, that was mostly userland stack trace collection in perf. I'll try to dig in archives and see what shows up - it's been a while ago...