Created attachment 146027 [details] Patch to add missing loop ioctls SUMMARY A Linux program using loopback device interface, when instrumented with valgrind, reports missing IOCTLS and routes the user to https://valgrind.org/docs/manual/dist.readme-missing.html. This bug-report is meant to bring the missing functionality into valgrind developers knowledge and to supply a supporting patch. STEPS TO REPRODUCE 1. Sample C program with steps to build and run is available at: https://gist.github.com/fsheikh/cd184450338f750af9e1a79f40b78419 2. Build above program with a C compiler e.g. "clang-10 -Wall -Werror loop_ioctls.c -o loop_ioctl" 3. Running the program with valgrind " valgrind ./loop_ioctl" OBSERVED RESULT ==28554== Memcheck, a memory error detector ==28554== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al. ==28554== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info ==28554== Command: ./loop_ioctl ==28554== Valgrind loopback test starting... ==28554== Warning: noted but unhandled ioctl 0x4c82 with no size/direction hints. ==28554== This could cause spurious value errors to appear. ==28554== See README_MISSING_SYSCALL_OR_IOCTL for guidance on writing a proper wrapper. Free loopback device /dev/loop32 found ==28554== Warning: noted but unhandled ioctl 0x4c01 with no size/direction hints. ==28554== This could cause spurious value errors to appear. ==28554== See README_MISSING_SYSCALL_OR_IOCTL for guidance on writing a proper wrapper. ==28554== Warning: noted but unhandled ioctl 0x4c09 with no size/direction hints. ==28554== This could cause spurious value errors to appear. ==28554== See README_MISSING_SYSCALL_OR_IOCTL for guidance on writing a proper wrapper. ==28554== Warning: noted but unhandled ioctl 0x4c05 with no size/direction hints. ==28554== This could cause spurious value errors to appear. ==28554== See README_MISSING_SYSCALL_OR_IOCTL for guidance on writing a proper wrapper. Valgrind loopback test done! ==28554== ==28554== HEAP SUMMARY: ==28554== in use at exit: 0 bytes in 0 blocks ==28554== total heap usage: 1 allocs, 1 frees, 1,024 bytes allocated ==28554== ==28554== All heap blocks were freed -- no leaks are possible ==28554== ==28554== For counts of detected and suppressed errors, rerun with: -v ==28554== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) EXPECTED RESULT valgrind does not generates warnings and memcheck tools is able to process a program containing loopback IOCTL(s) SOFTWARE/OS VERSIONS Ubuntu Linux (5.4.0-96-generic) ADDITIONAL INFORMATION Please see attachment for a proposed fix. Please do let me know if the patch needs to be sent to a mailing-list for review/approval or if it should be pushed to a public repository. Thanks!
Do you have a small testcase to exercise this code?
(In reply to Paul Floyd from comment #1) > Do you have a small testcase to exercise this code? Yes, please check the "STEPS TO REPRODUCE" section in bug description. There is a link including a small C program.
OK thanks I missed the link.
This all looks OK to me. Just one small problem - the testcase requires root privileges.
commit cb7adf4a9eaa06951afd8a066df3da6fcc095e5b (HEAD -> master, origin/master, origin/HEAD) Author: Paul Floyd <pjfloyd@wanadoo.fr> Date: Sun Mar 5 08:38:34 2023 +0100 Bug 449309 - Missing loopback device ioctl(s) Patch provided by: Faheem Sheikh <faheem.sheikh@bmw.de> Note that the testcase provided with this report hasn't been added as it requires privileges.