On Mon, Nov 14, 2011 at 02:48:41AM +0100, Bernhard Voelker wrote:
> [PATCH 11/15] prlimit: avoid segfault due to array-out-of-bounds error
>
> prlimit used 1 element of the lims array per limit given on the command
> line argument, not being aware that a user would pass the value of the
> soft and the hard limit in different options - leading to a segfault
> when the user passes more than MAX_RESOURCES limit options.
> As a side effect, a limit was retrieved and printed several times if
> the corresponding option appeared multiple times.
>
> Example:
> $ prlimit -l -l -l -l -l -l -l -l -l -l -l -l -l -l -l -l -l -l -l
> RESOURCE DESCRIPTION SOFT HARD UNITS
> MEMLOCK max locked-in-memory address space 65536 262144 bytes
> MEMLOCK max locked-in-memory address space 65536 262144 bytes
> ...
> Segmentation fault
Ah.. stupid bug.
> Use the lims array in a more direct way, i.e. the index is limit id.
> Initialize lims array and adapt option parsing in main() accordingly.
> do_prlimits() and show_limits(): loop over all MAX_RESOURCES in the
> lims array.
It means that users cannot control order of the printed and modified
resources. We prefer in all our new utils that output is fully
controlled by users -- only this is a way how you can create stable
and robust scripts.
I have replaced the array with list (see include/list.h). This
solution makes the code more readable and robust.
# ./prlimit --data --nofile
RESOURCE DESCRIPTION SOFT HARD UNITS
DATA max data size unlimited unlimited bytes
NOFILE max amount of open files 1001 3000
# ./prlimit --nofile --data
RESOURCE DESCRIPTION SOFT HARD UNITS
NOFILE max amount of open files 1001 3000
DATA max data size unlimited unlimited bytes
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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