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| author | Darrick J. Wong <djwong@us.ibm.com> | 2008-08-14 15:43:33 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-08-15 13:38:30 +0200 |
| commit | 967060d00d7ab8e992963a966cd3d18156c02d55 (patch) | |
| tree | c11b892999c65d8b1d805191f88b15bf4a058be2 /arch/x86/kernel/msr.c | |
| parent | a6825f1c1fa83b1e92b6715ee5771a4d6524d3b9 (diff) | |
| download | linux-967060d00d7ab8e992963a966cd3d18156c02d55.tar.gz linux-967060d00d7ab8e992963a966cd3d18156c02d55.tar.bz2 linux-967060d00d7ab8e992963a966cd3d18156c02d55.zip | |
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.c | 2 |
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; } /* |