Bug 7092 - ccache uses freed memory when compiling preprocessed file with errors
Summary: ccache uses freed memory when compiling preprocessed file with errors
Alias: None
Product: ccache
Classification: Unclassified
Component: ccache (show other bugs)
Version: 2.4
Hardware: Other Linux
: P3 normal
Target Milestone: 3.0
Assignee: Joel Rosdahl
QA Contact: Joel Rosdahl
Depends on:
Reported: 2010-02-02 17:51 UTC by Mike Frysinger
Modified: 2010-07-09 04:15 UTC (History)
0 users

See Also:


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Description Mike Frysinger 2010-02-02 17:51:46 UTC
take code that is preprocessed and has errors and feed it through ccache, and ccache will use freed memory with path names

for example:
$ echo 'main(){}' > test.c
$ ccache gcc -E test.c -o test.i
$ ccache gcc -c test.i
$ echo asdf > test.i
$ ccache gcc -c test.i
gcc: p��: No such file or directory
gcc: no input files

this is because the global variable "i_tmpfile" is added to orig_args, but when failed() is called, it assumes that the preprocessed file is always an intermediate and not the source, and thus free()'s it.  but orig_args->argv still wants to use i_tmpfile in its argv and so when the execve() is called, the string given down is garbage.

one fix is to simply avoid the i_tmpfile check in failed() and the associated free() ...

this can be seen in gdb by putting a break point on failed():
Breakpoint 1, failed () at ccache.c:100
100             if (i_tmpfile) {
(gdb) print orig_args->argv[0]@3
$6 = {0x60f8d0 "/usr/local/src/blackfin/toolchains/20100131/bfin-uclinux/bin/bfin-uclinux-gcc", 0x60f310 "-c", 0x60f2f0 "test.i"}
(gdb) print i_tmpfile
$7 = 0x60f2f0 "test.i"

see how orig_args->argv[2] is pointing to the same storage as i_tmpfile ...
Comment 1 Joel Rosdahl 2010-02-20 08:17:44 UTC
This bug has been fixed as a side-effect of commit befbba943b7d03a1b8e8858e22cb2dfce2ac7935.