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zfs_ioctl: saved_poolname can be truncated 

As it uses kmem_strdup() and kmem_strfree() which both rely on
strlen() being the same, but saved_poolname can be truncated causing:

SPL: kernel memory allocator:
buffer freed to wrong cache
SPL: buffer was allocated from kmem_alloc_16,
SPL: caller attempting free to kmem_alloc_8.
SPL: buffer=0xffffff90acc66a38  bufctl=0x0  cache: kmem_alloc_8

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Jorgen Lundman <lundman@lundman.net>
Closes #10469
This commit is contained in:
Jorgen Lundman 2020-06-18 06:30:03 +09:00 committed by GitHub
parent 17ca30185a
commit 4458157bee
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 14 additions and 11 deletions
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25
module/zfs/zfs_ioctl.c
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@ -7380,6 +7380,7 @@ zfsdev_ioctl_common(uint_t vecnum, zfs_cmd_t *zc, int flag)
int error, cmd;
const zfs_ioc_vec_t *vec;
char *saved_poolname = NULL;
size_t saved_poolname_len = 0;
nvlist_t *innvl = NULL;
fstrans_cookie_t cookie;
@ -7479,13 +7480,15 @@ zfsdev_ioctl_common(uint_t vecnum, zfs_cmd_t *zc, int flag)
goto out;
/* legacy ioctls can modify zc_name */
saved_poolname = kmem_strdup(zc->zc_name);
if (saved_poolname == NULL) {
error = SET_ERROR(ENOMEM);
goto out;
} else {
saved_poolname[strcspn(saved_poolname, "/@#")] = '\0';
}
/*
* Can't use kmem_strdup() as we might truncate the string and
* kmem_strfree() would then free with incorrect size.
*/
saved_poolname_len = strlen(zc->zc_name) + 1;
saved_poolname = kmem_alloc(saved_poolname_len, KM_SLEEP);
strlcpy(saved_poolname, zc->zc_name, saved_poolname_len);
saved_poolname[strcspn(saved_poolname, "/@#")] = '\0';
if (vec->zvec_func != NULL) {
nvlist_t *outnvl;
@ -7562,11 +7565,11 @@ out:
char *s = tsd_get(zfs_allow_log_key);
if (s != NULL)
kmem_strfree(s);
(void) tsd_set(zfs_allow_log_key, saved_poolname);
} else {
if (saved_poolname != NULL)
kmem_strfree(saved_poolname);
(void) tsd_set(zfs_allow_log_key, kmem_strdup(saved_poolname));
}
if (saved_poolname != NULL)
kmem_free(saved_poolname, saved_poolname_len);
return (error);
}