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authorThomas Gleixner <tglx@linutronix.de>2017-12-14 12:27:31 +0100
committerIngo Molnar <mingo@kernel.org>2017-12-22 20:13:01 +0100
commita4828f81037f491b2cc986595e3a969a6eeb2fb5 (patch)
tree32805595dc4cea937c2c918615b53193bbfdc4b2 /tools
parentc2b3496bb30bd159e9de42e5c952e1f1f33c9a77 (diff)
x86/ldt: Prevent LDT inheritance on exec
The LDT is inherited across fork() or exec(), but that makes no sense at all because exec() is supposed to start the process clean. The reason why this happens is that init_new_context_ldt() is called from init_new_context() which obviously needs to be called for both fork() and exec(). It would be surprising if anything relies on that behaviour, so it seems to be safe to remove that misfeature. Split the context initialization into two parts. Clear the LDT pointer and initialize the mutex from the general context init and move the LDT duplication to arch_dup_mmap() which is only called on fork(). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirsky <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: dan.j.williams@intel.com Cc: hughd@google.com Cc: keescook@google.com Cc: kirill.shutemov@linux.intel.com Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/x86/ldt_gdt.c9
1 files changed, 3 insertions, 6 deletions
diff --git a/tools/testing/selftests/x86/ldt_gdt.c b/tools/testing/selftests/x86/ldt_gdt.c
index 66e5ce5b91f0..0304ffb714f2 100644
--- a/tools/testing/selftests/x86/ldt_gdt.c
+++ b/tools/testing/selftests/x86/ldt_gdt.c
@@ -627,13 +627,10 @@ static void do_multicpu_tests(void)
static int finish_exec_test(void)
{
/*
- * In a sensible world, this would be check_invalid_segment(0, 1);
- * For better or for worse, though, the LDT is inherited across exec.
- * We can probably change this safely, but for now we test it.
+ * Older kernel versions did inherit the LDT on exec() which is
+ * wrong because exec() starts from a clean state.
*/
- check_valid_segment(0, 1,
- AR_DPL3 | AR_TYPE_XRCODE | AR_S | AR_P | AR_DB,
- 42, true);
+ check_invalid_segment(0, 1);
return nerrs ? 1 : 0;
}