On Mon, Mar 18, 2024 at 11:00 AM Nhat Pham <nphamcs@xxxxxxxxx> wrote: > > On Mon, Mar 18, 2024 at 9:58 AM syzbot > <syzbot+adbc983a1588b7805de3@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: e5eb28f6d1af Merge tag 'mm-nonmm-stable-2024-03-14-09-36' .. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=13043abe180000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=19bb57c23dffc38e > > dashboard link: https://syzkaller.appspot.com/bug?extid=adbc983a1588b7805de3 > > compiler: arm-linux-gnueabi-gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 > > userspace arch: arm > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1706d231180000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13ba7959180000 > > > > Downloadable assets: > > disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/8ead8862021c/non_bootable_disk-e5eb28f6.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/0a7371c63ff2/vmlinux-e5eb28f6.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/7539441b4add/zImage-e5eb28f6.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+adbc983a1588b7805de3@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > ------------[ cut here ]------------ > > kernel BUG at include/linux/scatterlist.h:187! > > Looks like the provided buffer is invalid: > > #ifdef CONFIG_DEBUG_SG > BUG_ON(!virt_addr_valid(buf)); > #endif > > which is "src" from: > > sg_init_one(&input, src, entry->length); > > Looking at the surrounding code and recent history, there's this > commit that stands out: > > mm/zswap: remove the memcpy if acomp is not sleepable > (sha: 270700dd06ca41a4779c19eb46608f076bb7d40e) > > which has the effect of, IIUC, using the zpool mapped memory directly > as src, instead of acomp_ctx->buffer (which was previously the case, > as zsmalloc was not sleepable). > > This might not necessarily be a bug with that commit itself, but might > have revealed another bug elsewhere. > > Anyway, cc-ing the author, Barry Song, to fact check me :) Will take a > closer look later. I am not a highmem expert, but the reproducer has CONFIG_HIGHMEM=y, and it seems like zs_map_object() may return a highmem address if the compressed object is entirely in a single page to avoid copying to a buffer: if (off + class->size <= PAGE_SIZE) { /* this object is contained entirely within a page */ area->vm_addr = kmap_atomic(page); ret = area->vm_addr + off; goto out; } The virt_addr_valid() check seems to indicate that we expect a direct map address in sg_init_one(), right?
