Hi,
On Thu, Mar 28, 2024 at 11:49:58PM +0300, Maks Mishin wrote:
> The descriptor 'dwfl_fd' is created at nm.c:1278 by calling
> function 'dup' and lost at nm.c:1593.
Sorry, I don't follow, the code at nm.c:1278 says:
/* Duplicate an fd for dwfl_report_offline to swallow. */
int dwfl_fd = dup (fd);
if (likely (dwfl_fd >= 0))
And then the code tracks whether the dwfl_report_offline call is
executed successfully and otherwise closed dwfl_fd. Specifically the
code does:
if (dwfl_report_offline (dwfl, fname, fname, dwfl_fd)
== NULL)
{
/* Consumed on success, not on failure. */
close (dwfl_fd);
}
The dwfl_report functions are documented as "On success, FD is
consumed by the library". Which means fd is freed/closed when dwfl_end
is called.
> Found by RASU JSC.
>
> Signed-off-by: Maks Mishin <[email protected]>
> ---
> src/nm.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/src/nm.c b/src/nm.c
> index 3675f59b..fee397dd 100644
> --- a/src/nm.c
> +++ b/src/nm.c
> @@ -1521,6 +1521,8 @@ show_symbols (int fd, Ebl *ebl, GElf_Ehdr *ehdr,
> }
> if (dwfl != NULL)
> dwfl_end (dwfl);
> + if (dwfl_fd != NULL)
> + close(dwfl_fd);
> }
So this would double close dwfl_fd. Also dwfl_fd is an int (file
descriptor) and so shouldn't be compared to NULL, but checked as above
(dwfl_fd >= 0).
