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Re: [PATCH] x86/hvm: Fix UBSAN failure in do_hvm_op() printk
- To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Wed, 31 Jan 2024 10:12:43 +0100
- Autocrypt: addr=jbeulich@xxxxxxxx; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL
- Cc: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Wed, 31 Jan 2024 09:12:49 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 30.01.2024 19:37, Andrew Cooper wrote:
> Tamas reported this UBSAN failure from fuzzing:
>
> (XEN)
> ================================================================================
> (XEN) UBSAN: Undefined behaviour in common/vsprintf.c:64:19
> (XEN) negation of -9223372036854775808 cannot be represented in type 'long
> long int':
> (XEN) ----[ Xen-4.19-unstable x86_64 debug=y ubsan=y Not tainted ]----
> ...
> (XEN) Xen call trace:
> (XEN) [<ffff82d040307c1c>] R ubsan.c#ubsan_epilogue+0xa/0xd9
> (XEN) [<ffff82d04030805d>] F __ubsan_handle_negate_overflow+0x99/0xce
> (XEN) [<ffff82d04028868f>] F vsprintf.c#number+0x10a/0x93e
> (XEN) [<ffff82d04028ac74>] F vsnprintf+0x19e2/0x1c56
> (XEN) [<ffff82d04030a47a>] F console.c#vprintk_common+0x76/0x34d
> (XEN) [<ffff82d04030a79e>] F printk+0x4d/0x4f
> (XEN) [<ffff82d04040c42b>] F do_hvm_op+0x288e/0x28f5
> (XEN) [<ffff82d04040d385>] F hvm_hypercall+0xad2/0x149a
> (XEN) [<ffff82d0403cd072>] F vmx_vmexit_handler+0x1596/0x279c
> (XEN) [<ffff82d0403d909b>] F vmx_asm_vmexit_handler+0xdb/0x200
>
> The problem is an unsigned -> signed converstion because of a bad
> formatter (%ld trying to format an unsigned long).
>
> We could fix it by swapping to %lu, but this is a useless printk() even in
> debug builds, so just drop it completely.
>
> Reported-by: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
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