lkml.org 
[lkml]   [1998]   [Oct]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: Linux 2.1.125 doesn't dump core on SIGSEGV
    On Tue, Oct 20, 1998 at 10:55:27PM +0100, David Woodhouse wrote:

    > In the coredump case, I'm not sure - but in general it's because
    > there's a race condition. Someone can put the 'evil' symlink in
    > place between the stat() and the open().

    No, indeed you are correct - there is a race. Doh! Need more coffee.

    > Even in the coredump case there's a race, but presumably there's a
    > lock somewhere that we can use to make it seem atomic.

    How does this look (still a race, but much harder to exploit):


    if(fd = (open("core",O_CREAT | O_EXCL)) == -1)
    goto end_dump;

    lstat("core",&fs1);
    fstat(fd,&fs2);

    /* compare stat results - don't sump if bad */


    Better?


    -cw

    We _really_ do need O_NOFOLLOW semantics. Anyone looked at how hard
    this would be to implement?




    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.rutgers.edu
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 13:45    [W:0.022 / U:30.196 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site