Messages in this thread | | | From | Masahiro Yamada <> | Date | Mon, 18 Dec 2017 22:58:49 +0900 | Subject | Re: [SIL2review] [PATCH] fixdep: free memory on second error path of do_config_file |
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2017-12-15 17:23 GMT+09:00 Nicholas Mc Guire <der.herr@hofr.at>: > On Thu, Dec 14, 2017 at 08:54:10PM +0100, Lukas Bulwahn wrote: >> Commit dee81e988674 ("fixdep: faster CONFIG_ search") introduces the memory >> leak when `map = mmap(...)` was replaced with `map = malloc(...)` and >> `read(fd, map, ...)`. It introduces a new second error path, which does not >> free the allocated memory for `map`. We now correct that behavior and free >> `map` before the do_config_file() function returns. >> >> Facebook's static analysis tool Infer (http://fbinfer.com) found this >> memory leak: >> >> scripts/basic/fixdep.c:297: error: MEMORY_LEAK >> memory dynamically allocated by call to `malloc()` at line 290, \ >> column 8 is not reachable after line 297, column 3. >> >> Fixes: dee81e988674 ("fixdep: faster CONFIG_ search") >> >> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com> > Reviewed-by: Nicholas Mc Guire <der.herr@hofr.at> > >> --- >> scripts/basic/fixdep.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c >> index bbf62cb..131c450 100644 >> --- a/scripts/basic/fixdep.c >> +++ b/scripts/basic/fixdep.c >> @@ -296,6 +296,7 @@ static void do_config_file(const char *filename) >> if (read(fd, map, st.st_size) != st.st_size) { >> perror("fixdep: read"); >> close(fd); >> + free(map); > > This looks reasonable but actually it is not clear why do_config_file() > should return at all if read fails as the read error would go unnoticed > in the current code and allow the build to continue. so this probably > should be an exit(2) here and not a return which would then take care > of the free() anyway.
I agree.
This should be exit(2).
You can also remove close() as well since the operation system will close it anyway.
> Atleast I do not see the rational to allow continuation if the read > failed as the file should not be empty nor a mismatch with st.st_size > expected. If it were due to a EINTR then it still should terminate as > EINTR was not handled and we thus could miss a valid dependency. > > Note: this probably also should be applied to the if (!map) condition > before as well, as at that point it is known that map > 0 and a malloc() > failure would allow skipping parse_config_file() for a valid config.
I agree. We should change this too.
-- Best Regards Masahiro Yamada
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