Re: [Crash-utility] [PATCH V2] netdump: fix regression for tiny kdump files
Hi, Qianli
Thanks for the patch.
在 2020年12月01日 14:45, crash-utility-request(a)redhat.com 写道:
Date: Tue, 1 Dec 2020 10:56:02 +0800
From: Qianli Zhao <zhaoqianligood(a)gmail.com>
To: crash-utility(a)redhat.com, minipli(a)grsecurity.net
Subject: [Crash-utility] [PATCH V2] netdump: fix regression for tiny
kdump files
Message-ID:
<1606791362-5604-1-git-send-email-zhaoqianligood(a)gmail.com>
Content-Type: text/plain; charset="US-ASCII"
From: Qianli Zhao <zhaoqianli(a)xiaomi.com>
Commit f42db6a33f0e ("Support core files with "unusual" layout")
increased the minimal file size from MIN_NETDUMP_ELF_HEADER_SIZE to
SAFE_NETDUMP_ELF_HEADER_SIZE which lead to crash rejecting very
small kdump files.
Good findings.
Fix that by erroring out only if we get less than
MIN_NETDUMP_ELF_HEADER_SIZE bytes.
Signed-off-by: Qianli Zhao <zhaoqianli(a)xiaomi.com>
---
- Update commit message
- Add more accurate judgment of read() return value
---
netdump.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/netdump.c b/netdump.c
index c76d9dd..9a36931 100644
--- a/netdump.c
+++ b/netdump.c
@@ -119,7 +119,8 @@ is_netdump(char *file, ulong source_query)
Elf64_Phdr *load64;
char *eheader, *sect0;
char buf[BUFSIZE];
- size_t size, len, tot;
+ ssize_t size;
+ size_t len, tot;
Elf32_Off offset32;
Elf64_Off offset64;
ulong format;
@@ -142,10 +143,14 @@ is_netdump(char *file, ulong source_query)
if (!read_flattened_format(fd, 0, eheader, size))
goto bailout;
} else {
- if (read(fd, eheader, size) != size) {
+ size = read(fd, eheader, size);
+ if (size < 0) {
sprintf(buf, "%s: ELF header read", file);
perror(buf);
goto bailout;
+ } else if (size < MIN_NETDUMP_ELF_HEADER_SIZE) {
For the checking condition, I would recommend using the following methods, what do you
think?
+ if (size != SAFE_NETDUMP_ELF_HEADER_SIZE &&
+ size != MIN_NETDUMP_ELF_HEADER_SIZE) {
sprintf(buf, "%s: ELF header read", file);
perror(buf);
goto bailout;
}
In addition, would you mind updating another error output in the is_netdump()? For
example:
size = SAFE_NETDUMP_ELF_HEADER_SIZE;
if ((eheader = (char *)malloc(size)) == NULL) {
- fprintf(stderr, "cannot malloc minimum ELF header buffer\n");
+ fprintf(stderr, "cannot malloc ELF header buffer\n");
clean_exit(1);
}
Thanks.
Lianbo
+ fprintf(stderr, "%s: file too small!\n", file);
+ goto bailout;
}
}
-- 2.7.4