Re: [PATCH v10 04/12] mm, arm64: untag user pointers passed to memory syscalls
From: Dave Hansen <hidden>
Date: 2019-02-22 23:07:50
Also in:
linux-arch, linux-doc, linux-kselftest, linux-mm, lkml
On 2/22/19 4:53 AM, Andrey Konovalov wrote:
quoted hunk ↗ jump to hunk
--- a/mm/mprotect.c +++ b/mm/mprotect.c@@ -578,6 +578,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len, SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, unsigned long, prot) { + start = untagged_addr(start); return do_mprotect_pkey(start, len, prot, -1); }@@ -586,6 +587,7 @@ SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len, unsigned long, prot, int, pkey) { + start = untagged_addr(start); return do_mprotect_pkey(start, len, prot, pkey); }
This seems to have taken the approach of going as close as possible to the syscall boundary and untagging the pointer there. I guess that's OK, but it does lead to more churn than necessary. For instance, why not just do the untagging in do_mprotect_pkey()? I think that's an overall design question. I kinda asked the same thing about patching call sites vs. VMA lookup functions. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel