* [PATCH] nm: Fix descriptor leak
@ 2024-03-28 20:49 Maks Mishin
2024-03-28 21:12 ` Mark Wielaard
0 siblings, 1 reply; 2+ messages in thread
From: Maks Mishin @ 2024-03-28 20:49 UTC (permalink / raw)
To: elfutils-devel; +Cc: Maks Mishin
The descriptor 'dwfl_fd' is created at nm.c:1278 by calling
function 'dup' and lost at nm.c:1593.
Found by RASU JSC.
Signed-off-by: Maks Mishin <maks.mishinFZ@gmail.com>
---
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);
}
--
2.30.2
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] nm: Fix descriptor leak
2024-03-28 20:49 [PATCH] nm: Fix descriptor leak Maks Mishin
@ 2024-03-28 21:12 ` Mark Wielaard
0 siblings, 0 replies; 2+ messages in thread
From: Mark Wielaard @ 2024-03-28 21:12 UTC (permalink / raw)
To: Maks Mishin; +Cc: elfutils-devel
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 <maks.mishinFZ@gmail.com>
> ---
> 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).
^ permalink raw reply [flat|nested] 2+ messages in thread
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