Description
In the Linux kernel, the following vulnerability has been resolved: vfs: fix race between evice_inodes() and find_inode()&iput() Hi, all Recently I noticed a bug[1] in btrfs, after digged it into and I believe it'a race in vfs. Let's assume there's a inode (ie ino 261) with i_count 1 is called by iput(), and there's a concurrent thread calling generic_shutdown_super(). cpu0: cpu1: iput() // i_count is 1 ->spin_lock(inode) ->dec i_count to 0 ->iput_final() generic_shutdown_super() ->__inode_add_lru() ->evict_inodes() // cause some reason[2] ->if (atomic_read(inode->i_count)) continue; // return before // inode 261 passed the above check // list_lru_add_obj() // and then schedule out ->spin_unlock() // note here: the inode 261 // was still at sb list and hash list, // and I_FREEING|I_WILL_FREE was not been set btrfs_iget() // after some function calls ->find_inode() // found the above inode 261 ->spin_lock(inode) // check I_FREEING|I_WILL_FREE // and passed ->__iget() ->spin_unlock(inode) // schedule back ->spin_lock(inode) // check (I_NEW|I_FREEING|I_WILL_FREE) flags, // passed and set I_FREEING iput() ->spin_unlock(inode) ->spin_lock(inode) ->evict() // dec i_count to 0 ->iput_final() ->spin_unlock() ->evict() Now, we have two threads simultaneously evicting the same inode, which may trigger the BUG(inode->i_state & I_CLEAR) statement both within clear_inode() and iput(). To fix the bug, recheck the inode->i_count after holding i_lock. Because in the most scenarios, the first check is valid, and the overhead of spin_lock() can be reduced. If there is any misunderstanding, please let me know, thanks. [1]: https://lore.kernel.org/linux-btrfs/[email protected]/ [2]: The reason might be 1. SB_ACTIVE was removed or 2. mapping_shrinkable() return false when I reproduced the bug.
Details
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| linux | — | 6.8.0-54.56 |
| linux-allwinner-5.19 | — | — |
| linux-aws | — | 6.8.0-1023.25 |
| linux-aws-5.0 | — | — |
| linux-aws-5.11 | — | — |
| linux-aws-5.13 | — | — |
| linux-aws-5.15 | — | 5.15.0-1073.79~20.04.1 |
| linux-aws-5.19 | — | — |
| linux-aws-5.3 | — | — |
| linux-aws-5.4 | — | 5.4.0-1142.152~18.04.1 |
| linux-aws-5.8 | — | — |
| linux-aws-6.2 | — | — |
| linux-aws-6.5 | — | — |
| linux-aws-6.8 | — | 6.8.0-1023.25~22.04.1 |
| linux-aws-fips | — | 5.15.0-1073.79+fips1 |
| linux-aws-hwe | — | — |
| linux-azure | — | 6.8.0-1025.30 |
| linux-azure-4.15 | — | — |
| linux-azure-5.11 | — | — |
| linux-azure-5.13 | — | — |
| linux-azure-5.15 | — | 5.15.0-1078.87~20.04.1 |
| linux-azure-5.19 | — | — |
| linux-azure-5.3 | — | — |
| linux-azure-5.4 | — | 5.4.0-1145.152~18.04.1 |
| linux-azure-5.8 | — | — |
| linux-azure-6.11 | — | 6.11.0-1012.12~24.04.1 |
| linux-azure-6.2 | — | — |
| linux-azure-6.5 | — | — |
| linux-azure-6.8 | — | 6.8.0-1025.30~22.04.1 |
| linux-azure-edge | — | — |
| linux-azure-fde | — | — |
| linux-azure-fde-5.19 | — | — |
| linux-azure-fde-6.2 | — | — |
| linux-azure-fips | — | 5.15.0-1078.87+fips1 |
| linux-azure-nvidia | — | 6.8.0-1014.15 |
| linux-bluefield | — | — |
| linux-fips | — | 6.8.0-78.78+fips1 |
| linux-gcp | — | 6.8.0-1024.26 |
| linux-gcp-4.15 | — | — |
| linux-gcp-5.11 | — | — |
| linux-gcp-5.13 | — | — |
| linux-gcp-5.15 | — | 5.15.0-1072.80~20.04.1 |
| linux-gcp-5.19 | — | — |
| linux-gcp-5.3 | — | — |
| linux-gcp-5.4 | — | 5.4.0-1143.152~18.04.1 |
| linux-gcp-5.8 | — | — |
| linux-gcp-6.11 | — | 6.11.0-1011.11~24.04.1 |
| linux-gcp-6.2 | — | — |
| linux-gcp-6.5 | — | — |
| linux-gcp-6.8 | — | 6.8.0-1024.26~22.04.1 |
| linux-gcp-fips | — | 5.15.0-1072.80+fips1 |
| linux-gke | — | 6.8.0-1019.23 |
| linux-gke-4.15 | — | — |
| linux-gke-5.15 | — | — |
| linux-gke-5.4 | — | — |
| linux-gkeop | — | 6.8.0-1006.8 |
| linux-gkeop-5.15 | — | — |
| linux-gkeop-5.4 | — | — |
| linux-hwe | — | — |
| linux-hwe-5.11 | — | — |
| linux-hwe-5.13 | — | — |
| linux-hwe-5.15 | — | 5.15.0-127.137~20.04.1 |
| linux-hwe-5.19 | — | — |
| linux-hwe-5.4 | — | 5.4.0-208.228~18.04.1 |
| linux-hwe-5.8 | — | — |
| linux-hwe-6.2 | — | — |
| linux-hwe-6.5 | — | — |
| linux-hwe-6.8 | — | 6.8.0-57.59~22.04.1 |
| linux-hwe-edge | — | — |
| linux-ibm | — | 6.8.0-1022.22 |
| linux-ibm-5.15 | — | 5.15.0-1066.69~20.04.1 |
| linux-ibm-5.4 | — | 5.4.0-1086.91~18.04.1 |
| linux-ibm-6.8 | — | 6.8.0-1023.23~22.04.1 |
| linux-intel-5.13 | — | — |
| linux-intel-iot-realtime | — | 5.15.0-1066.68 |
| linux-intel-iotg | — | 5.15.0-1071.77 |
| linux-intel-iotg-5.15 | — | 5.15.0-1071.77~20.04.1 |
| linux-iot | — | 5.4.0-1048.51 |
| linux-kvm | — | 5.15.0-1070.75 |
| linux-lowlatency | — | 6.8.0-54.56.1 |
| linux-lowlatency-hwe-5.15 | — | 5.15.0-127.137~20.04.1 |
| linux-lowlatency-hwe-5.19 | — | — |
| linux-lowlatency-hwe-6.2 | — | — |
| linux-lowlatency-hwe-6.5 | — | — |
| linux-lowlatency-hwe-6.8 | — | 6.8.0-54.56.1~22.04.1 |
| linux-lts-xenial | — | — |
| linux-nvidia | — | 6.8.0-1022.25 |
| linux-nvidia-6.11 | — | 6.11.0-1007.7 |
| linux-nvidia-6.2 | — | — |
| linux-nvidia-6.5 | — | — |
| linux-nvidia-6.8 | — | 6.8.0-1022.25~22.04.2 |
| linux-nvidia-lowlatency | — | 6.8.0-1022.25.2 |
| linux-nvidia-tegra | — | 5.15.0-1032.32 |
| linux-nvidia-tegra-5.15 | — | 5.15.0-1032.32~20.04.1 |
| linux-nvidia-tegra-igx | — | 5.15.0-1020.20 |
| linux-oem | — | — |
| linux-oem-5.10 | — | — |
| linux-oem-5.13 | — | — |
| linux-oem-5.14 | — | — |
| linux-oem-5.17 | — | — |
| linux-oem-5.6 | — | — |
| linux-oem-6.0 | — | — |
| linux-oem-6.1 | — | — |
| linux-oem-6.11 | — | 6.11.0-1015.15 |
| linux-oem-6.5 | — | — |
| linux-oem-6.8 | — | 6.8.0-1024.24 |
| linux-oracle | — | 6.8.0-1020.21 |
| linux-oracle-5.0 | — | — |
| linux-oracle-5.11 | — | — |
| linux-oracle-5.13 | — | — |
| linux-oracle-5.15 | — | 5.15.0-1071.77~20.04.1 |
| linux-oracle-5.3 | — | — |
| linux-oracle-5.4 | — | 5.4.0-1138.147~18.04.1 |
| linux-oracle-5.8 | — | — |
| linux-oracle-6.5 | — | — |
| linux-oracle-6.8 | — | 6.8.0-1020.21~22.04.1 |
| linux-raspi | — | 6.8.0-1019.23 |
| linux-raspi-5.4 | — | 5.4.0-1129.142~18.04.1 |
| linux-raspi-realtime | — | 6.8.0-2018.19 |
| linux-raspi2 | — | — |
| linux-realtime | — | 6.8.1-1016.17 |
| linux-realtime-6.8 | — | 6.8.1-1016.17~22.04.1 |
| linux-riscv | — | 6.8.0-53.55.1 |
| linux-riscv-5.11 | — | — |
| linux-riscv-5.15 | — | 5.15.0-1069.73~20.04.1 |
| linux-riscv-5.19 | — | — |
| linux-riscv-5.8 | — | — |
| linux-riscv-6.5 | — | — |
| linux-riscv-6.8 | — | 6.8.0-53.55.1~22.04.1 |
| linux-starfive-5.19 | — | — |
| linux-starfive-6.2 | — | — |
| linux-starfive-6.5 | — | — |
| linux-xilinx | — | 6.8.0-1017.18 |
| linux-xilinx-zynqmp | — | 5.15.0-1039.43 |
References
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