kexec-tools/kexec-tools-2.0.4-makedumpfile-memset-in-cyclic-bitmap-initialization-introdu.patch
WANG Chao 75c9162996 makedumpfile: memset() in cyclic bitmap initialization introduce segment fault.
This is a backport of the following upstream commit:

commit 4404368
Author: WANG Chao <chaowang@redhat.com>
Date:   Wed Dec 18 22:34:43 2013 +0900

    [PATCH] memset() in cyclic bitmap initialization introduce segment fault.

    We are using memset() to improve performance when creating 1st and 2nd
    bitmap. After doing round up the pfn_start and round down pfn_end, it's
    possible that pfn_start_roundup is greater than pfn_end_round. A segment
    fault could happen in that case because memset is taking roughly the
    value of (pfn_end_round << 3 - pfn_start_roundup << 3 ), which is
    negative, as its third argument.

    So we can skip the memset if start is greater than end. It's safe
    because we will set bit for the round up part and also round down part.

    Actually this happens on my EFI virtual machine:

    cat /proc/iomem:
    00000000-00000fff : reserved
    00001000-0009ffff : System RAM
    000a0000-000bffff : PCI Bus 0000:00
    000f0000-000fffff : System ROM
    00100000-3d162017 : System RAM
      01000000-015cab9b : Kernel code
      015cab9c-019beb3f : Kernel data
      01b4f000-01da9fff : Kernel bss
      30000000-37ffffff : Crash kernel
    3d162018-3d171e57 : System RAM
    3d171e58-3d172017 : System RAM
    3d172018-3d17ae57 : System RAM
    3d17ae58-3dc10fff : System RAM
    3dc11000-3dc18fff : reserved
    3dc19000-3dc41fff : System RAM
    3dc42000-3ddcefff : reserved
    3ddcf000-3f7fefff : System RAM
    3f7ff000-3f856fff : reserved
    [..]

    gdb ./makedumpfile core
    (gdb) bt full
    [..]
     #1  0x000000000042775d in create_1st_bitmap_cyclic () at makedumpfile.c:4543
            i = 0x5
            pfn = 0x3d190
            phys_start = 0x3d18ee58
            phys_end = 0x3d18f018
            pfn_start = 0x3d18e
            pfn_end = 0x3d18f
            pfn_start_roundup = 0x3d190
            pfn_end_round = 0x3d188
            pfn_start_byte = 0x7a32
            pfn_end_byte = 0x7a31
    [..]
    (gdb) list makedumpfile.c:4543
    4538                                        return FALSE;
    4539
    4540                        pfn_start_byte = (pfn_start_roundup - info->cyclic_start_pfn) >> 3;
    4541                        pfn_end_byte = (pfn_end_round - info->cyclic_start_pfn) >> 3;
    4542
    4543                        memset(info->partial_bitmap2 + pfn_start_byte,
    4544                               0xff,
    4545                               pfn_end_byte - pfn_start_byte);
    4546
    4547                        for (pfn = pfn_end_round; pfn < pfn_end; ++pfn)

    Signed-off-by: WANG Chao <chaowang@redhat.com>

This patch fixes segment fault issues on the systems with very small
memory map range (less than 8 pages).

Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-01-29 16:31:04 +08:00

113 lines
3.7 KiB
Diff

From 4404368a0860e3b6c845eb41782e97a9bf7593b8 Mon Sep 17 00:00:00 2001
From: WANG Chao <chaowang@redhat.com>
Date: Wed, 18 Dec 2013 22:34:43 +0900
Subject: [PATCH] [PATCH] memset() in cyclic bitmap initialization introduce
segment fault.
We are using memset() to improve performance when creating 1st and 2nd
bitmap. After doing round up the pfn_start and round down pfn_end, it's
possible that pfn_start_roundup is greater than pfn_end_round. A segment
fault could happen in that case because memset is taking roughly the
value of (pfn_end_round << 3 - pfn_start_roundup << 3 ), which is
negative, as its third argument.
So we can skip the memset if start is greater than end. It's safe
because we will set bit for the round up part and also round down part.
Actually this happens on my EFI virtual machine:
cat /proc/iomem:
00000000-00000fff : reserved
00001000-0009ffff : System RAM
000a0000-000bffff : PCI Bus 0000:00
000f0000-000fffff : System ROM
00100000-3d162017 : System RAM
01000000-015cab9b : Kernel code
015cab9c-019beb3f : Kernel data
01b4f000-01da9fff : Kernel bss
30000000-37ffffff : Crash kernel
3d162018-3d171e57 : System RAM
3d171e58-3d172017 : System RAM
3d172018-3d17ae57 : System RAM
3d17ae58-3dc10fff : System RAM
3dc11000-3dc18fff : reserved
3dc19000-3dc41fff : System RAM
3dc42000-3ddcefff : reserved
3ddcf000-3f7fefff : System RAM
3f7ff000-3f856fff : reserved
[..]
gdb ./makedumpfile core
(gdb) bt full
[..]
#1 0x000000000042775d in create_1st_bitmap_cyclic () at makedumpfile.c:4543
i = 0x5
pfn = 0x3d190
phys_start = 0x3d18ee58
phys_end = 0x3d18f018
pfn_start = 0x3d18e
pfn_end = 0x3d18f
pfn_start_roundup = 0x3d190
pfn_end_round = 0x3d188
pfn_start_byte = 0x7a32
pfn_end_byte = 0x7a31
[..]
(gdb) list makedumpfile.c:4543
4538 return FALSE;
4539
4540 pfn_start_byte = (pfn_start_roundup - info->cyclic_start_pfn) >>
3;
4541 pfn_end_byte = (pfn_end_round - info->cyclic_start_pfn) >> 3;
4542
4543 memset(info->partial_bitmap2 + pfn_start_byte,
4544 0xff,
4545 pfn_end_byte - pfn_start_byte);
4546
4547 for (pfn = pfn_end_round; pfn < pfn_end; ++pfn)
Signed-off-by: WANG Chao <chaowang@redhat.com>
---
makedumpfile.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/makedumpfile.c b/makedumpfile.c
index 23251a1..ef08d91 100644
--- a/makedumpfile-1.5.5/makedumpfile.c
+++ b/makedumpfile-1.5.5/makedumpfile.c
@@ -4435,11 +4435,13 @@ create_1st_bitmap_cyclic()
pfn_start_byte = (pfn_start_roundup - info->cyclic_start_pfn) >> 3;
pfn_end_byte = (pfn_end_round - info->cyclic_start_pfn) >> 3;
- memset(info->partial_bitmap1 + pfn_start_byte,
- 0xff,
- pfn_end_byte - pfn_start_byte);
+ if (pfn_start_byte < pfn_end_byte) {
+ memset(info->partial_bitmap1 + pfn_start_byte,
+ 0xff,
+ pfn_end_byte - pfn_start_byte);
- pfn_bitmap1 += (pfn_end_byte - pfn_start_byte) * BITPERBYTE;
+ pfn_bitmap1 += (pfn_end_byte - pfn_start_byte) * BITPERBYTE;
+ }
for (pfn = pfn_end_round; pfn < pfn_end; pfn++) {
if (set_bit_on_1st_bitmap(pfn))
@@ -4540,9 +4542,11 @@ initialize_2nd_bitmap_cyclic(void)
pfn_start_byte = (pfn_start_roundup - info->cyclic_start_pfn) >> 3;
pfn_end_byte = (pfn_end_round - info->cyclic_start_pfn) >> 3;
- memset(info->partial_bitmap2 + pfn_start_byte,
- 0xff,
- pfn_end_byte - pfn_start_byte);
+ if (pfn_start_byte < pfn_end_byte) {
+ memset(info->partial_bitmap2 + pfn_start_byte,
+ 0xff,
+ pfn_end_byte - pfn_start_byte);
+ }
for (pfn = pfn_end_round; pfn < pfn_end; ++pfn)
if (!set_bit_on_2nd_bitmap_for_kernel(pfn))
--
1.8.5.3