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authorDarrick J. Wong <djwong@us.ibm.com>2008-08-15 02:43:33 +0400
committerIngo Molnar <mingo@elte.hu>2008-08-15 15:38:30 +0400
commit967060d00d7ab8e992963a966cd3d18156c02d55 (patch)
treec11b892999c65d8b1d805191f88b15bf4a058be2 /arch/x86/kernel/msr.c
parenta6825f1c1fa83b1e92b6715ee5771a4d6524d3b9 (diff)
downloadlinux-967060d00d7ab8e992963a966cd3d18156c02d55.tar.xz
x86, msr: fix NULL pointer deref due to msr_open on nonexistent CPUs
msr_open tests for someone trying to open a device for a nonexistent CPU. However, the function always returns 0, not ret like it should, hence userspace can BUG the kernel trivially. This bug was introduced by the cdev lock_kernel pushdown patch last May. The BUG can be reproduced with these commands: # mknod fubar c 202 8 <-- pick a number less than NR_CPUS that is not the number of an online CPU # cat fubar Signed-off-by: Darrick J. Wong <djwong@us.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/msr.c')
-rw-r--r--arch/x86/kernel/msr.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 9fd809552447..e43938086885 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -131,7 +131,7 @@ static int msr_open(struct inode *inode, struct file *file)
ret = -EIO; /* MSR not supported */
out:
unlock_kernel();
- return 0;
+ return ret;
}
/*