Re: [f2fs-dev] [PATCH 1/2] f2fs: deallocate compressed pages when error happens

From: Chao Yu
Date: Mon Aug 30 2021 - 21:57:10 EST

Next message: tcs . kernel: "[PATCH] KVM: x86: Add a return code and check kvm_page_track_init We found a null pointer deref by our modified syzkaller. KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 1 PID: 13993 Comm: syz-executor.0 Kdump: loaded Tainted: G E 5.14.0-rc7+ #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 RIP: 0010:rcu_segcblist_enqueue+0xf5/0x1d0 build/../kernel/rcu/rcu_segcblist.c:348 RSP: 0018:ffffc90001e1fc10 EFLAGS: 00010046 RAX: dffffc0000000000 RBX: ffff888135c00080 RCX: ffffffff815ba8a1 RDX: 0000000000000000 RSI: ffffc90001e1fd00 RDI: ffff888135c00080 RBP: ffff888135c000a0 R08: 0000000000000004 R09: fffff520003c3f75 R10: 0000000000000003 R11: fffff520003c3f75 R12: 0000000000000000 R13: ffff888135c00080 R14: ffff888135c00040 R15: 0000000000000000 FS: 00007fecc99f1700(0000) GS:ffff888135c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2f225000 CR3: 0000000093d08000 CR4: 0000000000750ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: srcu_gp_start_if_needed+0x158/0xc60 build/../kernel/rcu/srcutree.c:823 __synchronize_srcu+0x1dc/0x250 build/../kernel/rcu/srcutree.c:929 kvm_mmu_uninit_vm+0x18/0x30 build/../arch/x86/kvm/mmu/mmu.c:5585 kvm_arch_destroy_vm+0x43f/0x5c0 build/../arch/x86/kvm/x86.c:11277 kvm_create_vm build/../arch/x86/kvm/../../../virt/kvm/kvm_main.c:1060 [inline] kvm_dev_ioctl_create_vm build/../arch/x86/kvm/../../../virt/kvm/kvm_main.c:4486 [inline] kvm_dev_ioctl+0xdfb/0x1860 build/../arch/x86/kvm/../../../virt/kvm/kvm_main.c:4541 vfs_ioctl build/../fs/ioctl.c:51 [inline] __do_sys_ioctl build/../fs/ioctl.c:1069 [inline] __se_sys_ioctl build/../fs/ioctl.c:1055 [inline] __x64_sys_ioctl+0x183/0x210 build/../fs/ioctl.c:1055 do_syscall_x64 build/../arch/x86/entry/common.c:50 [inline] do_syscall_64+0x34/0xb0 build/../arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae"
Previous message: Miaohe Lin: "Re: [PATCH 6/6] mm/page_alloc.c: avoid allocating highmem pages via alloc_pages_exact_nid()"
In reply to: Chao Yu: "Re: [f2fs-dev] [PATCH 2/2] f2fs: should put a page beyond EOF when preparing a write"
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On 2021/8/31 8:53, Jaegeuk Kim wrote:

In f2fs_write_multi_pages(), f2fs_compress_pages() allocates pages for
compression work in cc->cpages[]. Then, f2fs_write_compressed_pages() initiates
bio submission. But, if there's any error before submitting the IOs like early
f2fs_cp_error(), previously it didn't free cpages by f2fs_compress_free_page().
Let's fix memory leak by putting that just before deallocating cc->cpages.

Fixes: 4c8ff7095bef ("f2fs: support data compression")

Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>

Reviewed-by: Chao Yu <chao@xxxxxxxxxx>

Thanks,