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authorPaul Moore <paul@paul-moore.com>2017-11-28 18:51:12 -0500
committerPaul Moore <paul@paul-moore.com>2017-11-28 18:51:12 -0500
commitef28df55ac27e1e5cd122e19fa311d886d47a756 (patch)
tree61410c34607ca1bdf625b74467f1811f947f5690 /security/selinux/ss
parentsecurity: replace FSF address with web source in license notices (diff)
downloadlinux-dev-ef28df55ac27e1e5cd122e19fa311d886d47a756.tar.xz
linux-dev-ef28df55ac27e1e5cd122e19fa311d886d47a756.zip
selinux: ensure the context is NUL terminated in security_context_to_sid_core()
The syzbot/syzkaller automated tests found a problem in security_context_to_sid_core() during early boot (before we load the SELinux policy) where we could potentially feed context strings without NUL terminators into the strcmp() function. We already guard against this during normal operation (after the SELinux policy has been loaded) by making a copy of the context strings and explicitly adding a NUL terminator to the end. The patch extends this protection to the early boot case (no loaded policy) by moving the context copy earlier in security_context_to_sid_core(). Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Paul Moore <paul@paul-moore.com> Reviewed-By: William Roberts <william.c.roberts@intel.com>
Diffstat (limited to 'security/selinux/ss')
-rw-r--r--security/selinux/ss/services.c18
1 files changed, 8 insertions, 10 deletions
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 33cfe5d3d6cb..d05496deb229 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -1413,27 +1413,25 @@ static int security_context_to_sid_core(const char *scontext, u32 scontext_len,
if (!scontext_len)
return -EINVAL;
+ /* Copy the string to allow changes and ensure a NUL terminator */
+ scontext2 = kmemdup_nul(scontext, scontext_len, gfp_flags);
+ if (!scontext2)
+ return -ENOMEM;
+
if (!ss_initialized) {
int i;
for (i = 1; i < SECINITSID_NUM; i++) {
- if (!strcmp(initial_sid_to_string[i], scontext)) {
+ if (!strcmp(initial_sid_to_string[i], scontext2)) {
*sid = i;
- return 0;
+ goto out;
}
}
*sid = SECINITSID_KERNEL;
- return 0;
+ goto out;
}
*sid = SECSID_NULL;
- /* Copy the string so that we can modify the copy as we parse it. */
- scontext2 = kmalloc(scontext_len + 1, gfp_flags);
- if (!scontext2)
- return -ENOMEM;
- memcpy(scontext2, scontext, scontext_len);
- scontext2[scontext_len] = 0;
-
if (force) {
/* Save another copy for storing in uninterpreted form */
rc = -ENOMEM;