[Crash-utility] [PATCH V2] netdump: fix regression for tiny kdump files

[HAGIO KAZUHITO(萩尾 一仁)]

Hi Qianli,

Your patch is merged:
https://github.com/crash-utility/crash/commit/31ca172357c4d3520caf29b9efb5e6ccd622aae9

I've added the error message that you showed to the commit log.

Thanks,
Kazu

> -----Original Message-----
> From: crash-utility-bounces at redhat.com <crash-utility-bounces at redhat.com> On Behalf Of lijiang
> Sent: Wednesday, December 23, 2020 12:10 PM
> To: crash-utility at redhat.com
> Subject: Re: [Crash-utility] [PATCH V2] netdump: fix regression for tiny kdump files
> 
> 在 2020年12月23日 10:31, crash-utility-request at redhat.com 写道:
> > Date: Wed, 23 Dec 2020 02:31:24 +0000
> > From: ??? <zhaoqianli at xiaomi.com>
> > To: =?gb2312?B?SEFHSU8gS0FaVUhJVE8oyGPOsqGh0rvIyik=?=
> > 	<k-hagio-ab at nec.com>,	"Discussion list for crash utility usage,
> > 	maintenance and development"	<crash-utility at redhat.com>
> > Subject: Re: [Crash-utility] [External Mail]RE: [PATCH V2] netdump:
> > 	fix regression for tiny	kdump files
> > Message-ID: <e4cc6f753b2c428d9f0f0c0362567de5 at xiaomi.com>
> > Content-Type: text/plain; charset="gb2312"
> >
> > Hi, Lianbo
> >
> >
> >> 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) {
> > I agrre with Kazu, if use "size != MIN_NETDUMP_ELF_HEADER_SIZE/SAFE_NETDUMP_ELF_HEADER_SIZE"  this issue
> can not be fixed, size is equal to or more than MIN_NETDUMP_ELF_HEADER_SIZE is valid.
> >
> 
> That's true, I just knew what it happened. Thanks for the explanation.
> 
> >> 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);
> >>          }
> > Ok.
> >
> > How about below patch set?
> >
> 
> Looks good to me.
> Acked by: Lianbo Jiang <lijian at redhat.>
> 
> 
> >>From 5ec6ac06ba7fd32e96463a54ebc3f733f1054a90 Mon Sep 17 00:00:00 2001
> > From: Qianli Zhao <zhaoqianli at xiaomi.com>
> > Date: Mon, 30 Nov 2020 17:17:32 +0800
> > Subject: [PATCH] netdump: fix regression for tiny kdump files
> >
> > 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 can lead to crash rejecting
> > raw RAM dumpfiles
> >
> > Fix that by erroring out only if we get less than
> > MIN_NETDUMP_ELF_HEADER_SIZE bytes.
> >
> > Signed-off-by: Qianli Zhao <zhaoqianli at xiaomi.com>
> > ---
> >  netdump.c | 11 ++++++++---
> >  1 file changed, 8 insertions(+), 3 deletions(-)
> >
> > diff --git a/netdump.c b/netdump.c
> > index c76d9dd..ca9b459 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;
> > @@ -134,7 +135,7 @@ is_netdump(char *file, ulong source_query)
> >
> >         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);
> >          }
> >
> > @@ -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) {
> > +                       fprintf(stderr, "%s: file too small!\n", file);
> > +                       goto bailout;
> >                 }
> >         }
> >
> > --
> > 2.7.4
> 
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