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| author |   Zhang Zixun <zhang133010@icloud.com> | 2021-12-27 22:02:49 +0100 |
|---|---|---|
| committer |   Borislav Petkov <bp@suse.de> | 2021-12-28 11:45:36 +0100 |
| commit | de768416b203ac84e02a757b782a32efb388476f (patch) | |
| tree | 5ee61304bbe1f96dd423ef8e79749eda56ada6bc /arch/x86/kernel | |
| parent | x86/MCE/AMD, EDAC/mce_amd: Support non-uniform MCA bank type enumeration (diff) | |
| download | linux-dev-de768416b203ac84e02a757b782a32efb388476f.tar.xz linux-dev-de768416b203ac84e02a757b782a32efb388476f.zip | |
x86/mce/inject: Avoid out-of-bounds write when setting flags
A contrived zero-length write, for example, by using write(2):
...
ret = write(fd, str, 0);
...
to the "flags" file causes:
BUG: KASAN: stack-out-of-bounds in flags_write
Write of size 1 at addr ffff888019be7ddf by task writefile/3787
CPU: 4 PID: 3787 Comm: writefile Not tainted 5.16.0-rc7+ #12
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
due to accessing buf one char before its start.
Prevent such out-of-bounds access.
[ bp: Productize into a proper patch. Link below is the next best
thing because the original mail didn't get archived on lore. ]
Fixes: 0451d14d0561 ("EDAC, mce_amd_inj: Modify flags attribute to use string arguments")
Signed-off-by: Zhang Zixun <zhang133010@icloud.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/linux-edac/YcnePfF1OOqoQwrX@zn.tnic/
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/cpu/mce/inject.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/mce/inject.c b/arch/x86/kernel/cpu/mce/inject.c index 6eac840c64bb..5fbd7ffb3233 100644 --- a/arch/x86/kernel/cpu/mce/inject.c +++ b/arch/x86/kernel/cpu/mce/inject.c @@ -363,7 +363,7 @@ static ssize_t flags_write(struct file *filp, const char __user *ubuf, char buf[MAX_FLAG_OPT_SIZE], *__buf; int err; - if (cnt > MAX_FLAG_OPT_SIZE) + if (!cnt || cnt > MAX_FLAG_OPT_SIZE) return -EINVAL; if (copy_from_user(&buf, ubuf, cnt)) |