[PATCH 5.10 620/717] um: Remove use of asprinf in umid.c

Greg Kroah-Hartman
2020-12-28T14:28:58Z

From: Anton Ivanov <anton.ivanov@cambridgegreys.com>

commit 97be7ceaf7fea68104824b6aa874cff235333ac1 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/um/os-Linux/umid.c | 17 +++++------------
1 file changed, 5 insertions(+), 12 deletions(-)

--- 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 *di
{
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;
+ file = malloc(filelen);
+ if (!file)
+ return -ENOMEM;

- filelen = strlen(file);
-
- 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);