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Message-ID: <20260227201826.30098-1-mailto.luca.kellermann@gmail.com>
Date: Fri, 27 Feb 2026 21:17:15 +0100
From: Luca Kellermann <mailto.luca.kellermann@...il.com>
To: Rich Felker <dalias@...c.org>
Cc: musl@...ts.openwall.com
Subject: [PATCH] scandir: fix qsort usage
calling qsort() with a pointer to a function whose type is not
compatible with int(const void *, const void *) results in UB because
qsort() would call this function with an incompatible type.
avoid this by using qsort_r(). this is similar to how qsort() is
implemented on top of qsort_r().
the casts to void * in wrapper_cmp() are required because scandir()
takes int (*)(const struct dirent **, const struct dirent **) and not
int (*)(const struct dirent *const *, const struct dirent *const *).
---
Since you haven't posted a patch yet, I went ahead and fixed this. The
patch is based on the scandir() patch series I submitted in July.
src/dirent/scandir.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/src/dirent/scandir.c b/src/dirent/scandir.c
index 9e4e623f..993e0c8b 100644
--- a/src/dirent/scandir.c
+++ b/src/dirent/scandir.c
@@ -7,9 +7,15 @@
#include <errno.h>
#include <stddef.h>
+typedef int (*cmpfun)(const struct dirent **, const struct dirent **);
+
+static int wrapper_cmp(const void *de1, const void *de2, void *cmp)
+{
+ return ((cmpfun)cmp)((void *)de1, (void *)de2);
+}
+
int scandir(const char *path, struct dirent ***res,
- int (*sel)(const struct dirent *),
- int (*cmp)(const struct dirent **, const struct dirent **))
+ int (*sel)(const struct dirent *), cmpfun cmp)
{
DIR *d;
struct dirent *de, **names=0, **tmp;
@@ -70,7 +76,7 @@ int scandir(const char *path, struct dirent ***res,
/* cmp() and caller must not observe that errno was set to 0. */
errno = old_errno;
- if (cmp) qsort(names, cnt, sizeof *names, (int (*)(const void *, const void *))cmp);
+ if (cmp) __qsort_r(names, cnt, sizeof *names, wrapper_cmp, (void *)cmp);
*res = names;
return cnt;
}
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