[Crash-utility] [External Mail][????] Re: [PATCH] netdump: bugfix for read elf header
赵乾利
zhaoqianli at xiaomi.com
Mon Nov 30 13:50:28 UTC 2020
Hi,
> This looks like an error to me. According to the above errno value, you
> tried to read a file that's not there? But maybe it's just a stall errno
> value as we don't reset it prior to calling read(). To clarify, can you
> please provide the output of running 'strace crash ....'?
Please found below strace,read size only 232,it's less then "SAFE_NETDUMP_ELF_HEADER_SIZE".
open("DDRCS0_0.BIN", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0744, st_size=2147483648, ...}) = 0
open("DDRCS1_0.BIN", O_RDONLY) = 4
fstat(4, {st_mode=S_IFREG|0744, st_size=2147483648, ...}) = 0
open("/var/tmp/ramdump_elf_viw34m", O_RDWR|O_CREAT|O_EXCL, 0600) = 5
write(5, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\4\0\267\0\1\0\0\0\0\0\0\0\0\0\0\0"..., 232) = 232
close(5) = 0
open("/var/tmp/ramdump_elf_viw34m", O_RDWR) = 5
read(5, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\4\0\267\0\1\0\0\0\0\0\0\0\0\0\0\0"..., 304) = 232
dup(2) = 6
fcntl(6, F_GETFL) = 0x8002 (flags O_RDWR|O_LARGEFILE)
fstat(6, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 1), ...}) = 0
write(6, "/var/tmp/ramdump_elf_viw34m: ELF"..., 72/var/tmp/ramdump_elf_viw34m: ELF header read: No such file or directory
) = 72
close(6) = 0
close(5) = 0
write(1, "crash: malformed ELF file: /var/"..., 55crash: malformed ELF file: /var/tmp/ramdump_elf_viw34m
) = 55
write(1, "\nUsage:\n\n", 9
Usage:
) = 9
write(1, " crash [OPTION]... NAMELIST MEM"..., 68 crash [OPTION]... NAMELIST MEMORY-IMAGE[@ADDRESS] (dumpfile form)
) = 68
write(1, " crash [OPTION]... [NAMELIST] "..., 64 crash [OPTION]... [NAMELIST] (live system form)
) = 64
write(1, "\n", 1
) = 1
write(1, "Enter \"crash -h\" for details.\n", 30Enter "crash -h" for details.
) = 30
unlink("/var/tmp/ramdump_elf_viw34m") = 0
exit_group(1) = ?
+++ exited with 1 +++
> Anyhow,this change introduces a regression to the code that's following, which
> assumes the full 'size' was read, like the sanity checks for finding the
> PT_NOTE program header. So you should either update 'size' so it mirrors
> the actual bytes read or double-check that the kdump file you're trying
> to analyze is actually a real one.
After apply the patch,issue is gone,so it's not kdump files problem.
How about below patch set?
commit 8daecb704fa37a17e3c5294e35e593bfc1545016
Author: Qianli Zhao <zhaoqianli at xiaomi.com>
Date: Mon Nov 30 17:17:32 2020 +0800
netdump: bugfix for read elf header
Without the patch,errors may occur in reading the ELF header,
causing the parsing to fail.header file size may smaller than
SAFE_NETDUMP_ELF_HEADER_SIZE
Signed-off-by: Qianli Zhao <zhaoqianli at xiaomi.com>
diff --git a/netdump.c b/netdump.c
index c76d9dd..2e3e255 100644
--- a/netdump.c
+++ b/netdump.c
@@ -142,7 +142,7 @@ is_netdump(char *file, ulong source_query)
if (!read_flattened_format(fd, 0, eheader, size))
goto bailout;
} else {
- if (read(fd, eheader, size) != size) {
+ if ((size = read(fd, eheader, size)) < MIN_NETDUMP_ELF_HEADER_SIZE) {
sprintf(buf, "%s: ELF header read", file);
perror(buf);
goto bailout;
________________________________
From: crash-utility-bounces at redhat.com <crash-utility-bounces at redhat.com> on behalf of Mathias Krause <minipli at grsecurity.net>
Sent: Monday, November 30, 2020 20:28
To: Qianli Zhao; crash-utility at redhat.com
Subject: [External Mail][????] Re: [Crash-utility] [PATCH] netdump: bugfix for read elf header
Hi,
Am 30.11.20 um 11:56 schrieb Qianli Zhao:
> From: Qianli Zhao <zhaoqianli at xiaomi.com>
>
> Without the patch,errors may occur in reading the ELF header,
> causing the parsing to fail.
>
> Signed-off-by: Qianli Zhao <zhaoqianli at xiaomi.com>
> ---
> When i use crash to parsing a kdump,i got below error.
> This error occurs because of the read header less then SAFE_NETDUMP_ELF_HEADER_SIZE,
> But can read MIN_NETDUMP_ELF_HEADER_SIZE bytes from the file correctly.
> this issue is introduced due to commit:f42db6a33f0e0652df7cce8506352745b4794287
>
> crash 7.2.9
> Copyright (C) 2002-2020 Red Hat, Inc.
> Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
> Copyright (C) 1999-2006 Hewlett-Packard Co
> Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
> Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
> Copyright (C) 2005, 2011 NEC Corporation
> Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
> Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
> This program is free software, covered by the GNU General Public License,
> and you are welcome to change it and/or distribute copies of it under
> certain conditions. Enter "help copying" to see the conditions.
> This program has absolutely no warranty. Enter "help warranty" for details.
>
> /var/tmp/ramdump_elf_B2R4cQ: ELF header read: No such file or directory
> crash: malformed ELF file: /var/tmp/ramdump_elf_B2R4cQ
This looks like an error to me. According to the above errno value, you
tried to read a file that's not there? But maybe it's just a stall errno
value as we don't reset it prior to calling read(). To clarify, can you
please provide the output of running 'strace crash ....'?
>
> Usage:
>
> crash [OPTION]... NAMELIST MEMORY-IMAGE[@ADDRESS] (dumpfile form)
> crash [OPTION]... [NAMELIST] (live system form)
>
> Enter "crash -h" for details.
>
> ---
> netdump.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/netdump.c b/netdump.c
> diff --git a/netdump.c b/netdump.c
> index c76d9dd..cb0af41 100644
> --- a/netdump.c
> +++ b/netdump.c
> @@ -142,7 +142,7 @@ is_netdump(char *file, ulong source_query)
> if (!read_flattened_format(fd, 0, eheader, size))
> goto bailout;
> } else {
> - if (read(fd, eheader, size) != size) {
> + if (read(fd, eheader, size) < MIN_NETDUMP_ELF_HEADER_SIZE) {
size -- which is set to SAFE_NETDUMP_ELF_HEADER_SIZE here -- is only 128
bytes more than MIN_NETDUMP_ELF_HEADER_SIZE. This means, if the above
change really fixes your issue, you're trying to open a very small file
that barely carries any useful information beside its header. Anyhow,
this change introduces a regression to the code that's following, which
assumes the full 'size' was read, like the sanity checks for finding the
PT_NOTE program header. So you should either update 'size' so it mirrors
the actual bytes read or double-check that the kdump file you're trying
to analyze is actually a real one.
Thanks,
Mathias
> sprintf(buf, "%s: ELF header read", file);
> perror(buf);
> goto bailout;
>
--
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