Patch "s390/crashdump: fix TOD programmable field size" has been added to the 4.14-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    s390/crashdump: fix TOD programmable field size

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     s390-crashdump-fix-tod-programmable-field-size.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit d15c729766a4332f30049091c2890531271d4605
Author: Heiko Carstens <hca@xxxxxxxxxxxxx>
Date:   Fri Nov 18 13:05:39 2022 +0100

    s390/crashdump: fix TOD programmable field size
    
    [ Upstream commit f44e07a8afdd713ddc1a8832c39372fe5dd86895 ]
    
    The size of the TOD programmable field was incorrectly increased from
    four to eight bytes with commit 1a2c5840acf9 ("s390/dump: cleanup CPU
    save area handling").
    This leads to an elf notes section NT_S390_TODPREG which has a size of
    eight instead of four bytes in case of kdump, however even worse is
    that the contents is incorrect: it is supposed to contain only the
    contents of the TOD programmable field, but in fact contains a mix of
    the TOD programmable field (32 bit upper bits) and parts of the CPU
    timer register (lower 32 bits).
    
    Fix this by simply changing the size of the todpreg field within the
    save area structure. This will implicitly also fix the size of the
    corresponding elf notes sections.
    
    This also gets rid of this compile time warning:
    
    in function ‘fortify_memcpy_chk’,
        inlined from ‘save_area_add_regs’ at arch/s390/kernel/crash_dump.c:99:2:
    ./include/linux/fortify-string.h:413:25: error: call to ‘__read_overflow2_field’
       declared with attribute warning: detected read beyond size of field
       (2nd parameter); maybe use struct_group()? [-Werror=attribute-warning]
      413 |                         __read_overflow2_field(q_size_field, size);
          |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    
    Fixes: 1a2c5840acf9 ("s390/dump: cleanup CPU save area handling")
    Reviewed-by: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
    Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
    Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index 9b0216d571ad..feb8f332b55c 100644
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -45,7 +45,7 @@ struct save_area {
 	u64 fprs[16];
 	u32 fpc;
 	u32 prefix;
-	u64 todpreg;
+	u32 todpreg;
 	u64 timer;
 	u64 todcmp;
 	u64 vxrs_low[16];