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#357 Segmentation faults when logging in using smartcard

Future
open
Henrik Andersson
Internals (36)
5
2012-07-28
2012-07-24
rkron
No

I can succesfully connect to a Windows TS using rdesktpp 1.7.1.
But when smartcard must be used to login, rdesktop crashes after having entered the PIN code, reporting a segmentation fault.

This can be fixed easily in the next version of rdesktop by adding a condition test in the body of the SC_xfreeallmemory function in the scard.c file.
the xfree call must be conditional, test that the datasize of the handle is not zero. This will do, rdesktop remains stable after that.

setup is tested with rdesktop package 1.7.1 downloaded from rdesktop.org, pcsc-litepackage 1.5.2-7, smartcard driver ccid package 1.3.9, and glibc package 1.12-1.80, on a laptop running 64 bits RHEL 6

Discussion

  • rkron

    rkron - 2012-07-26

    bugfixed code

     
    scard.c

  • rkron

    rkron - 2012-07-26

    Upoloaded the file containing the bugfix (line 424).
    rdesktop session remained stable the whole working day.

     

  • Henrik Andersson

    Henrik Andersson - 2012-07-28
    • assigned_to: nobody --> hean01
     

  • Henrik Andersson

    Henrik Andersson - 2012-07-28

    Hi Rob,

    I just reviewed your fix and it looks wrong, memory will never be freed
    due to the condition will always evaluated as false because of the previous
    memset() which zeroes out the memory area.

    I can't reproduce the fail so it would be nice if you can revert and provide a
    backtrace for your crash.

     

  • rkron

    rkron - 2012-07-29

    screenshot of smartcard login prompt

     
    Thumbnail
    rdesktop_scard_login.png

  • rkron

    rkron - 2012-07-29

    debug trace of smart card login session

     
    rdesktop171_scard_debug_trace_201207291455.txt

  • rkron

    rkron - 2012-07-29

    configure command options and logging

     
    rdesktop171_configure_201207291445.txt

  • rkron

    rkron - 2012-07-29

    make output

     
    rdesktop171_make_201207291450.txt

  • rkron

    rkron - 2012-07-29

    Hi Henrik,

    As requested, a smartcard debug trace file is attached. A ascreenshot of the smatrcard login dialog is also present. Hopefully this will do for you?
    After entering the PIN the segmentation fault occors and the RDP session is terminated.

    Of course a proper memory management is important, but at the moment I would not worry about memory not being freed properly, the rdesktop program is being used on a Lenovo Thinkpad T420 with 8Gb memory installed.

    Fyi, the segmentation fault also occurs when using rdesktop 1.6.0.