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All local variables storing the head and the tail have been modified to unsigned short too the best of my knowledge) pipe_resize_ring() has added a check to make sure nr_slots can be contained within the limits of the pipe->{head,tail}. Building on that, pipe->{max_usage,ring_size} were also converted to unsigned short to catch any cases of incorrect unsigned arithmetic. This has been tested for a few hours with anon pipes on a 5th Generation AMD EPYC System and on a dual socket Intel Granite Rapids system without experiencing any obvious issues. pipe_write() was tagged with a debug trace_printk() on one of the test machines to make sure the head has indeed wrapped around behind the tail to ensure the wraparound scenarios are indeed happening. Few pipe_occupancy() and pipe->max_usage based checks have been converted to use unsigned short based arithmetic in fs/fuse/dev.c, fs/splice.c, mm/filemap.c, and mm/filemap.c. Few of the observations from Rasmus on a parallel thread [1] has been folded into Patch 3 (thanks a ton for chasing them). More eyes and testing is greatly appreciated. If my tests run into any issues, I'll report back on this thread. Series was tested with: hackbench -g 16 -f 20 --threads --pipe -l 10000000 -s 100 # Warp around stress-ng --oom-pipe 128 --oom-pipe-ops 100000 -t 600s # pipe resize stress-ng --splice 128 --splice-ops 100000000 -t 600s # splice stress-ng --vm-splice 128 --vm-splice-ops 100000000 -t 600s # splice stress-ng --tee 128 --tee-ops 100000000 -t 600s stress-ng --zlib 128 --zlib-ops 1000000 -t 600s stress-ng --sigpipe 128 -t 60s stress-ng did not report any failure in my testing. [1] https://lore.kernel.org/all/87cyeu5zgk.fsf@prevas.dk/ -- K Prateek Nayak (3): fs/pipe: Limit the slots in pipe_resize_ring() fs/splice: Atomically read pipe->{head,tail} in opipe_prep() treewide: pipe: Convert all references to pipe->{head,tail,max_usage,ring_size} to unsigned short fs/fuse/dev.c | 4 +++- fs/pipe.c | 33 +++++++++++++++----------- fs/splice.c | 50 ++++++++++++++++++++------------------- include/linux/pipe_fs_i.h | 39 ++++++++++-------------------- kernel/watch_queue.c | 3 ++- mm/filemap.c | 5 ++-- mm/shmem.c | 5 ++-- 7 files changed, 69 insertions(+), 70 deletions(-) base-commit: 848e076317446f9c663771ddec142d7c2eb4cb43 -- 2.43.0