[PATCH] alpha: fix several security issues

Dan Rosenberg
2011-06-11T18:52:20Z

Fix several security issues in Alpha-specific syscalls. Untested, but
mostly trivial.

1. Signedness issue in osf_getdomainname allows copying out-of-bounds
kernel memory to userland.

2. Signedness issue in osf_sysinfo allows copying large amounts of
kernel memory to userland.

3. Typo (?) in osf_getsysinfo bounds minimum instead of maximum copy
size, allowing copying large amounts of kernel memory to userland.

4. Usage of user pointer in osf_wait4 while under KERNEL_DS allows
privilege escalation via writing return value of sys_wait4 to kernel
memory.

Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
---
arch/alpha/kernel/osf_sys.c | 11 +++++++----
1 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index 376f221..98fb16d 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -409,7 +409,7 @@ SYSCALL_DEFINE2(osf_getdomainname, char __user *, name, int, namelen)
return -EFAULT;

len = namelen;
- if (namelen > 32)
+ if (len > 32)
len = 32;

down_read(&uts_sem);
@@ -594,7 +594,7 @@ SYSCALL_DEFINE3(osf_sysinfo, int, command, char __user *, buf, long, count)
down_read(&uts_sem);
res = sysinfo_table[offset];
len = strlen(res)+1;
- if (len > count)
+ if ((unsigned long)len > (unsigned long)count)
len = count;
if (copy_to_user(buf, res, len))
err = -EFAULT;
@@ -649,7 +649,7 @@ SYSCALL_DEFINE5(osf_getsysinfo, unsigned long, op, void __user *, buffer,
return 1;

case GSI_GET_HWRPB:
- if (nbytes < sizeof(*hwrpb))
+ if (nbytes > sizeof(*hwrpb))
return -EINVAL;
if (copy_to_user(buffer, hwrpb, nbytes) != 0)
return -EFAULT;
@@ -1008,6 +1008,7 @@ SYSCALL_DEFINE4(osf_wait4, pid_t, pid, int __user *, ustatus, int, options,
{
struct rusage r;
long ret, err;
+ unsigned int status = 0;
mm_segment_t old_fs;

if (!ur)
@@ -1016,13 +1017,15 @@ SYSCALL_DEFINE4(osf_wait4, pid_t, pid, int __user *, ustatus, int, options,
old_fs = get_fs();

set_fs (KERNEL_DS);
- ret = sys_wait4(pid, ustatus, options, (struct rusage __user *) &r);
+ ret = sys_wait4(pid, (unsigned int __user *) &status, options,
+ (struct rusage __user *) &r);
set_fs (old_fs);

if (!access_ok(VERIFY_WRITE, ur, sizeof(*ur)))
return -EFAULT;

err = 0;
+ err |= put_user(status, ustatus);
err |= __put_user(r.ru_utime.tv_sec, &ur->ru_utime.tv_sec);
err |= __put_user(r.ru_utime.tv_usec, &ur->ru_utime.tv_usec);
err |= __put_user(r.ru_stime.tv_sec, &ur->ru_stime.tv_sec);