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authorJann Horn <jannh@google.com>2018-06-25 19:34:10 +0300
committerEric W. Biederman <ebiederm@xmission.com>2018-08-11 10:05:53 +0300
commit42a0cc3478584d4d63f68f2f5af021ddbea771fa (patch)
tree8dc33625ea1c8488e01965f159ef3f597eba42cb /arch/sparc
parent5820f140edef111a9ea2ef414ab2428b8cb805b1 (diff)
downloadlinux-42a0cc3478584d4d63f68f2f5af021ddbea771fa.tar.xz
sys: don't hold uts_sem while accessing userspace memory
Holding uts_sem as a writer while accessing userspace memory allows a namespace admin to stall all processes that attempt to take uts_sem. Instead, move data through stack buffers and don't access userspace memory while uts_sem is held. Cc: stable@vger.kernel.org Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'arch/sparc')
-rw-r--r--arch/sparc/kernel/sys_sparc_32.c22
-rw-r--r--arch/sparc/kernel/sys_sparc_64.c20
2 files changed, 25 insertions, 17 deletions
diff --git a/arch/sparc/kernel/sys_sparc_32.c b/arch/sparc/kernel/sys_sparc_32.c
index 7f3d9c59719a..452e4d080855 100644
--- a/arch/sparc/kernel/sys_sparc_32.c
+++ b/arch/sparc/kernel/sys_sparc_32.c
@@ -197,23 +197,27 @@ SYSCALL_DEFINE5(rt_sigaction, int, sig,
SYSCALL_DEFINE2(getdomainname, char __user *, name, int, len)
{
- int nlen, err;
-
+ int nlen, err;
+ char tmp[__NEW_UTS_LEN + 1];
+
if (len < 0)
return -EINVAL;
- down_read(&uts_sem);
-
+ down_read(&uts_sem);
+
nlen = strlen(utsname()->domainname) + 1;
err = -EINVAL;
if (nlen > len)
- goto out;
+ goto out_unlock;
+ memcpy(tmp, utsname()->domainname, nlen);
- err = -EFAULT;
- if (!copy_to_user(name, utsname()->domainname, nlen))
- err = 0;
+ up_read(&uts_sem);
-out:
+ if (copy_to_user(name, tmp, nlen))
+ return -EFAULT;
+ return 0;
+
+out_unlock:
up_read(&uts_sem);
return err;
}
diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index 63baa8aa9414..274ed0b9b3e0 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -519,23 +519,27 @@ asmlinkage void sparc_breakpoint(struct pt_regs *regs)
SYSCALL_DEFINE2(getdomainname, char __user *, name, int, len)
{
- int nlen, err;
+ int nlen, err;
+ char tmp[__NEW_UTS_LEN + 1];
if (len < 0)
return -EINVAL;
- down_read(&uts_sem);
-
+ down_read(&uts_sem);
+
nlen = strlen(utsname()->domainname) + 1;
err = -EINVAL;
if (nlen > len)
- goto out;
+ goto out_unlock;
+ memcpy(tmp, utsname()->domainname, nlen);
+
+ up_read(&uts_sem);
- err = -EFAULT;
- if (!copy_to_user(name, utsname()->domainname, nlen))
- err = 0;
+ if (copy_to_user(name, tmp, nlen))
+ return -EFAULT;
+ return 0;
-out:
+out_unlock:
up_read(&uts_sem);
return err;
}