* Re: Bug reporting
[not found] <1621111620246345@mail.yandex.ru>
@ 2021-05-05 22:37 ` Alejandro Colomar (man-pages)
[not found] ` <1492841620310804@mail.yandex.ru>
0 siblings, 1 reply; 6+ messages in thread
From: Alejandro Colomar (man-pages) @ 2021-05-05 22:37 UTC (permalink / raw)
To: Dave Chupreev
Cc: linux-man, GNU C Library, Michael Kerrisk (man-pages), Roland McGrath
[ added a few CCs ]
Hello Dave,
On 5/5/21 10:30 PM, Dave Chupreev wrote:
> Hello, Alejandro.
>
> On page 138
I guess you refer to TLPI, written by Michael.
>
> 1.
>
> Your version of /unsetenv() /should check to see whether there
> are multiple definitions of an environment variable, and remove
> them all.
>
> How can I add such variables which have many definitions? According to
> *putenv* and *setenv* functions, variables with the same names are
> replaced if encountered.
I haven't read that part of the book yet, so I ignore the context. But
AFAIK, that can't happen on Linux, as you pointed out (probably neither
on Unix systems in general, but I don't know for sure, probably Michael
does). I guess the only possibility is if an attacker somehow modified
your environment and inserted multiple copies of an env variable.
The book (TLPI) states that glibc does check that, so I digged into the
sources and found that in <stdlib/setenv.c>, around line 290
(<https://sourceware.org/git?p=glibc.git;a=blob;f=stdlib/setenv.c;h=893f081af6b5a21b999a4056757fd69d1386c0d4;hb=HEAD#l290>).
That behavior was introduced by Roland in commit
196980f5117c8d38f10d64bf67eeb0924651675f
(<https://sourceware.org/git/?p=glibc.git;a=commit;h=196980f5117c8d38f10d64bf67eeb0924651675f>),
so maybe he can better explain the reasons behind the change (the commit
msg is quite unexplicative) if he still remembers (that goes back to 1995).
Regards,
Alex
--
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Bug reporting
[not found] ` <1492841620310804@mail.yandex.ru>
@ 2021-05-09 16:40 ` Michael Kerrisk (man-pages)
2021-05-09 17:20 ` Alexander Monakov
0 siblings, 1 reply; 6+ messages in thread
From: Michael Kerrisk (man-pages) @ 2021-05-09 16:40 UTC (permalink / raw)
To: Dave Chupreev
Cc: Alejandro Colomar (man-pages), linux-man, GNU C Library, Roland McGrath
Hello,
On Fri, 7 May 2021 at 02:21, Dave Chupreev <cdn.dev@yandex.ru> wrote:
>
> Well I see, I've tried on Linux and yea I didn't find any option to insert multiple definitions.
I think the only way to insert multiple definitions is by direct
manipulation of 'extern char **environ'.
Thanks,
Michael
> 06.05.2021, 01:37, "Alejandro Colomar (man-pages)" <alx.manpages@gmail.com>:
>
> [ added a few CCs ]
>
> Hello Dave,
>
> On 5/5/21 10:30 PM, Dave Chupreev wrote:
>
> Hello, Alejandro.
>
> On page 138
>
>
> I guess you refer to TLPI, written by Michael.
>
>
> 1.
>
> Your version of /unsetenv() /should check to see whether there
> are multiple definitions of an environment variable, and remove
> them all.
>
> How can I add such variables which have many definitions? According to
> *putenv* and *setenv* functions, variables with the same names are
> replaced if encountered.
>
>
> I haven't read that part of the book yet, so I ignore the context. But
> AFAIK, that can't happen on Linux, as you pointed out (probably neither
> on Unix systems in general, but I don't know for sure, probably Michael
> does). I guess the only possibility is if an attacker somehow modified
> your environment and inserted multiple copies of an env variable.
>
> The book (TLPI) states that glibc does check that, so I digged into the
> sources and found that in <stdlib/setenv.c>, around line 290
> (<https://sourceware.org/git?p=glibc.git;a=blob;f=stdlib/setenv.c;h=893f081af6b5a21b999a4056757fd69d1386c0d4;hb=HEAD#l290>).
> That behavior was introduced by Roland in commit
> 196980f5117c8d38f10d64bf67eeb0924651675f
> (<https://sourceware.org/git/?p=glibc.git;a=commit;h=196980f5117c8d38f10d64bf67eeb0924651675f>),
> so maybe he can better explain the reasons behind the change (the commit
> msg is quite unexplicative) if he still remembers (that goes back to 1995).
>
> Regards,
>
> Alex
>
> --
> Alejandro Colomar
> Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
> http://www.alejandro-colomar.es/
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Bug reporting
2021-05-09 16:40 ` Michael Kerrisk (man-pages)
@ 2021-05-09 17:20 ` Alexander Monakov
2021-05-09 17:58 ` Michael Kerrisk (man-pages)
0 siblings, 1 reply; 6+ messages in thread
From: Alexander Monakov @ 2021-05-09 17:20 UTC (permalink / raw)
To: mtk.manpages
Cc: Dave Chupreev, Alejandro Colomar (man-pages),
linux-man, GNU C Library, Roland McGrath
On Mon, 10 May 2021, Michael Kerrisk (man-pages) via Libc-alpha wrote:
> Hello,
>
> On Fri, 7 May 2021 at 02:21, Dave Chupreev <cdn.dev@yandex.ru> wrote:
> >
> > Well I see, I've tried on Linux and yea I didn't find any option to insert multiple definitions.
>
> I think the only way to insert multiple definitions is by direct
> manipulation of 'extern char **environ'.
You can cause a program to start with multiple definitions, because it is
possible to pass arbitrarily funny stuff as 'envp' argument to execve, such as:
- duplicated entries
- entries without a '='
- entries starting with '='
- empty strings
- "2 x 2 = 4"
All of that will be present in the exec'd program's environment array.
Alexander
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Bug reporting
2021-05-09 17:20 ` Alexander Monakov
@ 2021-05-09 17:58 ` Michael Kerrisk (man-pages)
0 siblings, 0 replies; 6+ messages in thread
From: Michael Kerrisk (man-pages) @ 2021-05-09 17:58 UTC (permalink / raw)
To: Alexander Monakov
Cc: Dave Chupreev, Alejandro Colomar (man-pages),
linux-man, GNU C Library, Roland McGrath
Hello ALexander,
On Mon, 10 May 2021 at 05:20, Alexander Monakov <amonakov@ispras.ru> wrote:
>
>
>
> On Mon, 10 May 2021, Michael Kerrisk (man-pages) via Libc-alpha wrote:
>
> > Hello,
> >
> > On Fri, 7 May 2021 at 02:21, Dave Chupreev <cdn.dev@yandex.ru> wrote:
> > >
> > > Well I see, I've tried on Linux and yea I didn't find any option to insert multiple definitions.
> >
> > I think the only way to insert multiple definitions is by direct
> > manipulation of 'extern char **environ'.
>
> You can cause a program to start with multiple definitions, because it is
> possible to pass arbitrarily funny stuff as 'envp' argument to execve, such as:
>
> - duplicated entries
> - entries without a '='
> - entries starting with '='
> - empty strings
> - "2 x 2 = 4"
>
> All of that will be present in the exec'd program's environment array.
Yes. I was too focussed on thinking about what an already running
program can do to its current environment. Thanks for reminding me of
the above.
Thanks,
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: bug reporting
2014-09-26 13:41 bug reporting Ajay
@ 2014-09-26 23:51 ` brian m. carlson
0 siblings, 0 replies; 6+ messages in thread
From: brian m. carlson @ 2014-09-26 23:51 UTC (permalink / raw)
To: Ajay; +Cc: git
[-- Attachment #1: Type: text/plain, Size: 1366 bytes --]
On Fri, Sep 26, 2014 at 07:11:35PM +0530, Ajay wrote:
> Hello,
>
> I have faced a git bug. When I try to clone a git repo it shows an
> error "protocol error: bad pack header".
>
> This is the full error message which I got while cloning git
> project :
>
> Clone: protocol error: bad pack header
> $ git clone -v --progress
> http://dev.galaxylipl.com:88/galaxygit/privatenovator.git
> /home/lipl/privateschoolinnovator
> Cloning into '/home/lipl/privatenovator'...
> POST git-upload-pack (190 bytes)
> remote: error: Could not read e9a6c4c684a5e8758026e8b0e25867c03332fe7c
> remote: fatal: bad tree object e9a6c4c684a5e8758026e8b0e25867c03332fe7c
> remote: aborting due to possible repository corruption on the remote
> side.
> protocol error: bad pack header
This indicates some sort of corruption between the client and server. I
notice you're cloning over HTTP. Are you using a proxy? Can you try
using a git, ssh, or https (without MITM) URL? Sometimes broken proxies
can end up corrupting data.
Also, what version of git are you using on the client and the server?
--
brian m. carlson / brian with sandals: Houston, Texas, US
+1 832 623 2791 | http://www.crustytoothpaste.net/~bmc | My opinion only
OpenPGP: RSA v4 4096b: 88AC E9B2 9196 305B A994 7552 F1BA 225C 0223 B187
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]
^ permalink raw reply [flat|nested] 6+ messages in thread
* bug reporting
@ 2014-09-26 13:41 Ajay
2014-09-26 23:51 ` brian m. carlson
0 siblings, 1 reply; 6+ messages in thread
From: Ajay @ 2014-09-26 13:41 UTC (permalink / raw)
To: git
Hello,
I have faced a git bug. When I try to clone a git repo it
shows an error "protocol error: bad pack header".
This is the full error message which I got while cloning git
project :
Clone: protocol error: bad pack header
$ git clone -v --progress
http://dev.galaxylipl.com:88/galaxygit/privatenovator.git
/home/lipl/privateschoolinnovator
Cloning into '/home/lipl/privatenovator'...
POST git-upload-pack (190 bytes)
remote: error: Could not read e9a6c4c684a5e8758026e8b0e25867c03332fe7c
remote: fatal: bad tree object
e9a6c4c684a5e8758026e8b0e25867c03332fe7c
remote: aborting due to possible repository corruption on the
remote side.
protocol error: bad pack header
I tried everything to resolve this error, I have run some commands on
server side like :
# git fsck
# git-fsck --full
# git fsck --lost-found
# git repack
# git gc
But nothing worked for me and the error is still same. I tried
to find the corrupt file but I was unable to find.
Please check this issue and provide me proper solution for this.
Thanks & Regards,
Ajay Dadgas
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-05-09 17:58 UTC | newest]
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[not found] <1621111620246345@mail.yandex.ru>
2021-05-05 22:37 ` Bug reporting Alejandro Colomar (man-pages)
[not found] ` <1492841620310804@mail.yandex.ru>
2021-05-09 16:40 ` Michael Kerrisk (man-pages)
2021-05-09 17:20 ` Alexander Monakov
2021-05-09 17:58 ` Michael Kerrisk (man-pages)
2014-09-26 13:41 bug reporting Ajay
2014-09-26 23:51 ` brian m. carlson
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