From: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Date: Fri, 13 Nov 2020 10:26:17 +0000 (+0000)
Subject: um: Remove use of asprinf in umid.c
X-Git-Tag: v5.11-rc1~71^2~28
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=97be7ceaf7fea68104824b6aa874cff235333ac1;p=thirdparty%2Flinux.git

um: Remove use of asprinf in umid.c

asprintf is not compatible with the existing uml memory allocation
mechanism. Its use on the "user" side of UML results in a corrupt slab
state.

Fixes: 0d4e5ac7e780 ("um: remove uses of variable length arrays")
Cc: stable@vger.kernel.org
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
---

diff --git a/arch/um/os-Linux/umid.c b/arch/um/os-Linux/umid.c
index 1d7558dac75f3..a3dd61521d240 100644
--- a/arch/um/os-Linux/umid.c
+++ b/arch/um/os-Linux/umid.c
@@ -137,20 +137,13 @@ static inline int is_umdir_used(char *dir)
 {
 	char pid[sizeof("nnnnnnnnn")], *end, *file;
 	int dead, fd, p, n, err;
-	size_t filelen;
+	size_t filelen = strlen(dir) + sizeof("/pid") + 1;
 
-	err = asprintf(&file, "%s/pid", dir);
-	if (err < 0)
-		return 0;
-
-	filelen = strlen(file);
+	file = malloc(filelen);
+	if (!file)
+		return -ENOMEM;
 
-	n = snprintf(file, filelen, "%s/pid", dir);
-	if (n >= filelen) {
-		printk(UM_KERN_ERR "is_umdir_used - pid filename too long\n");
-		err = -E2BIG;
-		goto out;
-	}
+	snprintf(file, filelen, "%s/pid", dir);
 
 	dead = 0;
 	fd = open(file, O_RDONLY);