In the Linux kernel, the following vulnerability has been resolved:
netfs: Only call folio_start_fscache() one time for each folio
If a network filesystem using netfs implements a clamp_length() function, it can set subrequest lengths smaller than a page size.
When we loop through the folios in netfs_rreq_unlock_folios() to set any folios to be written back, we need to make sure we only call folio_start_fscache() once for each folio.
Otherwise, this simple testcase:
mount -o fsc,rsize=1024,wsize=1024 127.0.0.1:/export /mnt/nfs dd if=/dev/zero of=/mnt/nfs/file.bin bs=4096 count=1 1+0 records in 1+0 records out 4096 bytes (4.1 kB, 4.0 KiB) copied, 0.0126359 s, 324 kB/s echo 3 > /proc/sys/vm/drop_caches cat /mnt/nfs/file.bin > /dev/null
will trigger an oops similar to the following:
page dumped because: VM_BUG_ON_FOLIO(folio_test_private_2(folio)) ------------[ cut here ]------------ kernel BUG at include/linux/netfs.h:44! ... CPU: 5 PID: 134 Comm: kworker/u16:5 Kdump: loaded Not tainted 6.4.0-rc5 ... RIP: 0010:netfs_rreq_unlock_folios+0x68e/0x730 [netfs] ... Call Trace: netfs_rreq_assess+0x497/0x660 [netfs] netfs_subreq_terminated+0x32b/0x610 [netfs] nfs_netfs_read_completion+0x14e/0x1a0 [nfs] nfs_read_completion+0x2f9/0x330 [nfs] rpc_free_task+0x72/0xa0 [sunrpc] rpc_async_release+0x46/0x70 [sunrpc] process_one_work+0x3bd/0x710 worker_thread+0x89/0x610 kthread+0x181/0x1c0 ret_from_fork+0x29/0x50
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade perf-debuginfoUpgrade kernel-modules-extraUpgrade kernel-debuginfoUpgrade bpftool-debuginfoUpgrade kernel-debuginfo-common-aarch64Upgrade bpftoolUpgrade kernel-libbpfUpgrade kernel-livepatch-6.1.56-82.125Upgrade kernel-tools-debuginfoUpgrade kernel-headersUpgrade kernel-debuginfo-common-x86_64Upgrade python3-perf-debuginfoUpgrade kernel-develUpgrade kernel-libbpf-develUpgrade kernel-toolsUpgrade kernel-libbpf-staticUpgrade python3-perfUpgrade perfUpgrade kernelUpgrade kernel-tools-devel | Feb 17, 2025 | Mar 2, 2024 |
| Debian | — | Upgrade linux | Jul 30, 2024 | Mar 2, 2024 |
| Redhat_linux | — | No solution exists | Jul 9, 2025 | Mar 2, 2024 |
| Suse | — | Upgrade dtb-amlogicUpgrade kernel-devel-azureUpgrade kernel-source-vanillaUpgrade kernel-debug-livepatch-develUpgrade kernel-azure-livepatch-develUpgrade cluster-md-kmp-defaultUpgrade kernel-azure-vdsoUpgrade kernel-rt-livepatch-develUpgrade dtb-qcomUpgrade kernel-kvmsmall-vdsoUpgrade kernel-rt_debug-vdsoUpgrade kernel-syms-azureUpgrade dlm-kmp-64kbUpgrade dtb-nvidiaUpgrade kernel-default-livepatchUpgrade kselftests-kmp-64kbUpgrade kernel-default-extraUpgrade kernel-source-rtUpgrade kernel-sourceUpgrade dlm-kmp-azureUpgrade kernel-syms-rtUpgrade kernel-azure-develUpgrade kernel-rt_debugUpgrade kernel-azure-optionalUpgrade dtb-broadcomUpgrade dtb-rockchipUpgrade dtb-sprdUpgrade kselftests-kmp-azureUpgrade kernel-kvmsmallUpgrade dtb-exynosUpgrade kernel-rt-vdsoUpgrade kernel-rt-extraUpgrade kernel-azureUpgrade kernel-obs-buildUpgrade kernel-rt-optionalUpgrade ocfs2-kmp-64kbUpgrade kernel-default-vdsoUpgrade reiserfs-kmp-azureUpgrade kernel-defaultUpgrade kernel-rt_debug-develUpgrade reiserfs-kmp-64kbUpgrade kernel-macrosUpgrade kernel-rtUpgrade dlm-kmp-rtUpgrade dtb-marvellUpgrade kernel-docs-htmlUpgrade kernel-debug-vdsoUpgrade kernel-default-base-rebuildUpgrade cluster-md-kmp-64kbUpgrade kernel-zfcpdumpUpgrade kernel-default-livepatch-develUpgrade kernel-64kb-extraUpgrade kernel-azure-extraUpgrade kselftests-kmp-defaultUpgrade kernel-source-azureUpgrade dtb-hisiliconUpgrade gfs2-kmp-rtUpgrade dtb-xilinxUpgrade kernel-64kb-develUpgrade dtb-allwinnerUpgrade dtb-freescaleUpgrade kernel-develUpgrade reiserfs-kmp-defaultUpgrade dtb-mediatekUpgrade dtb-amdUpgrade kernel-obs-qaUpgrade gfs2-kmp-64kbUpgrade dtb-alteraUpgrade kernel-rt-livepatchUpgrade dlm-kmp-defaultUpgrade kernel-rt-develUpgrade kernel-kvmsmall-livepatch-develUpgrade kernel-kvmsmall-develUpgrade kernel-default-optionalUpgrade kernel-debugUpgrade gfs2-kmp-azureUpgrade dtb-socionextUpgrade dtb-renesasUpgrade dtb-caviumUpgrade dtb-amazonUpgrade cluster-md-kmp-azureUpgrade ocfs2-kmp-rtUpgrade kselftests-kmp-rtUpgrade gfs2-kmp-defaultUpgrade kernel-symsUpgrade ocfs2-kmp-defaultUpgrade kernel-rt_debug-livepatch-develUpgrade dtb-appleUpgrade dtb-lgUpgrade kernel-docsUpgrade kernel-default-develUpgrade kernel-64kb-livepatch-develUpgrade reiserfs-kmp-rtUpgrade kernel-devel-rtUpgrade kernel-default-baseUpgrade kernel-debug-develUpgrade dtb-armUpgrade ocfs2-kmp-azureUpgrade kernel-64kb-optionalUpgrade kernel-64kbUpgrade dtb-apmUpgrade cluster-md-kmp-rt | Apr 17, 2024 | Mar 2, 2024 |
| Ubuntu | — | Upgrade linux-nvidia-6.5 | Nov 19, 2024 | Mar 2, 2024 |
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