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x86-64: Fill unused parts of the vsyscall page with 0xcc 

Jumping to 0x00 might do something depending on the following
bytes. Jumping to 0xcc is a trap.  So fill the unused parts of
the vsyscall page with 0xcc to make it useless for exploits to
jump there.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Jesper Juhl <jj@chaosbits.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: richard -rw- weinberger <richard.weinberger@gmail.com>
Cc: Mikael Pettersson <mikpe@it.uu.se>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Louis Rilling <Louis.Rilling@kerlabs.com>
Cc: Valdis.Kletnieks@vt.edu
Cc: pageexec@freemail.hu
Link: http://lkml.kernel.org/r/ed54bfcfbe50a9070d20ec1edbe0d149e22a4568.1307292171.git.luto@mit.edu
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Andy Lutomirski 2011-06-05 13:50:23 -04:00 committed by Ingo Molnar
parent bb5fe2f78e
commit 5dfcea629a
1 changed files with 8 additions and 10 deletions
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18
arch/x86/kernel/vmlinux.lds.S
View File

@ -166,22 +166,20 @@ SECTIONS
__vsyscall_0 = .;
. = VSYSCALL_ADDR;
.vsyscall_0 : AT(VLOAD(.vsyscall_0)) {
.vsyscall : AT(VLOAD(.vsyscall)) {
*(.vsyscall_0)
} :user
. = ALIGN(L1_CACHE_BYTES);
.vsyscall_fn : AT(VLOAD(.vsyscall_fn)) {
. = ALIGN(L1_CACHE_BYTES);
*(.vsyscall_fn)
}
.vsyscall_1 ADDR(.vsyscall_0) + 1024: AT(VLOAD(.vsyscall_1)) {
. = 1024;
*(.vsyscall_1)
}
.vsyscall_2 ADDR(.vsyscall_0) + 2048: AT(VLOAD(.vsyscall_2)) {
*(.vsyscall_2)
}
. = 2048;
*(.vsyscall_2)
. = 4096; /* Pad the whole page. */
} :user =0xcc
. = ALIGN(__vsyscall_0 + PAGE_SIZE, PAGE_SIZE);
#undef VSYSCALL_ADDR