Hello,
Commit 6c3b7af1c975b87b86dcb2af233d1ae21eb05107 ("kyber: add tracepoints")[1] causes write beyond size of object. This was detected by "FORTIFY_SOURCE intra-object overflow checking"[2] feature which is part of linux-hardened out-of-tree patchset designed to catch such errors.
The specific error is:
In file included from ./include/linux/bitmap.h:9,
from ./include/linux/cpumask.h:12,
from ./arch/x86/include/asm/cpumask.h:5,
from ./arch/x86/include/asm/msr.h:11,
from ./arch/x86/include/asm/processor.h:21,
from ./arch/x86/include/asm/cpufeature.h:8,
from ./arch/x86/include/asm/thread_info.h:53,
from ./include/linux/thread_info.h:38,
from ./arch/x86/include/asm/preempt.h:7,
from ./include/linux/preempt.h:81,
from ./include/linux/rcupdate.h:40,
from ./include/linux/rculist.h:11,
from ./include/linux/pid.h:5,
from ./include/linux/sched.h:14,
from ./include/linux/blkdev.h:5,
from block/kyber-iosched.c:21:
In function ‘strlcpy’,
inlined from ‘perf_trace_kyber_latency’ at ./include/trace/events/kyber.h:14:1:
./include/linux/string.h:310:4: error: call to ‘__write_overflow’ declared with attribute error: detected write beyond size of object passed as 1st parameter
__write_overflow();
^~~~~~~~~~~~~~~~~~
In function ‘strlcpy’,
inlined from ‘trace_event_raw_event_kyber_latency’ at ./include/trace/events/kyber.h:14:1:
./include/linux/string.h:310:4: error: call to ‘__write_overflow’ declared with attribute error: detected write beyond size of object passed as 1st parameter
__write_overflow();
^~~~~~~~~~~~~~~~~~
make[1]: *** [scripts/Makefile.build:293: block/kyber-iosched.o] Error 1
make: *** [Makefile:1063: block] Error 2
make: *** Waiting for unfinished jobs....
Using 'strlcpy' function is generally not recommended[3][4].
Jordan
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v4.20-rc1&id=6c3b7af1c975b87b86dcb2af233d1ae21eb05107
[2] https://github.com/anthraxx/linux-hardened/commit/9460692de8eb53fd62d59f564eba215e7c03a34b
[3] https://lwn.net/Articles/763641/
[4] https://outflux.net/slides/2018/lss/danger.pdf
