This is a note to let you know that I've just added the patch titled
net: filter: s390: fix JIT address randomization
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-filter-s390-fix-jit-address-randomization.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Wed May 28 21:03:54 PDT 2014
From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Date: Wed, 14 May 2014 09:48:21 +0200
Subject: net: filter: s390: fix JIT address randomization
From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
[ Upstream commit e84d2f8d2ae33c8215429824e1ecf24cbca9645e ]
This is the s390 variant of Alexei's JIT bug fix.
(patch description below stolen from Alexei's patch)
bpf_alloc_binary() adds 128 bytes of room to JITed program image
and rounds it up to the nearest page size. If image size is close
to page size (like 4000), it is rounded to two pages:
round_up(4000 + 4 + 128) == 8192
then 'hole' is computed as 8192 - (4000 + 4) = 4188
If prandom_u32() % hole selects a number >= PAGE_SIZE - sizeof(*header)
then kernel will crash during bpf_jit_free():
kernel BUG at arch/x86/mm/pageattr.c:887!
Call Trace:
[<ffffffff81037285>] change_page_attr_set_clr+0x135/0x460
[<ffffffff81694cc0>] ? _raw_spin_unlock_irq+0x30/0x50
[<ffffffff810378ff>] set_memory_rw+0x2f/0x40
[<ffffffffa01a0d8d>] bpf_jit_free_deferred+0x2d/0x60
[<ffffffff8106bf98>] process_one_work+0x1d8/0x6a0
[<ffffffff8106bf38>] ? process_one_work+0x178/0x6a0
[<ffffffff8106c90c>] worker_thread+0x11c/0x370
since bpf_jit_free() does:
unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK;
struct bpf_binary_header *header = (void *)addr;
to compute start address of 'bpf_binary_header'
and header->pages will pass junk to:
set_memory_rw(addr, header->pages);
Fix it by making sure that &header->image[prandom_u32() % hole] and &header
are in the same page.
Fixes: aa2d2c73c21f2 ("s390/bpf,jit: address randomize and write protect jit code")
Reported-by: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v3.11+
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/net/bpf_jit_comp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -811,7 +811,7 @@ static struct bpf_binary_header *bpf_all
return NULL;
memset(header, 0, sz);
header->pages = sz / PAGE_SIZE;
- hole = sz - (bpfsize + sizeof(*header));
+ hole = min(sz - (bpfsize + sizeof(*header)), PAGE_SIZE - sizeof(*header));
/* Insert random number of illegal instructions before BPF code
* and make sure the first instruction starts at an even address.
*/
Patches currently in stable-queue which might be from heiko.carstens@xxxxxxxxxx are
queue-3.14/net-filter-s390-fix-jit-address-randomization.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html