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chaseyuJaegeuk Kim
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f2fs: fix to do sanity check on block address in f2fs_do_zero_range()
As Yanming reported in bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215894 I have encountered a bug in F2FS file system in kernel v5.17. I have uploaded the system call sequence as case.c, and a fuzzed image can be found in google net disk The kernel should enable CONFIG_KASAN=y and CONFIG_KASAN_INLINE=y. You can reproduce the bug by running the following commands: kernel BUG at fs/f2fs/segment.c:2291! Call Trace: f2fs_invalidate_blocks+0x193/0x2d0 f2fs_fallocate+0x2593/0x4a70 vfs_fallocate+0x2a5/0xac0 ksys_fallocate+0x35/0x70 __x64_sys_fallocate+0x8e/0xf0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae The root cause is, after image was fuzzed, block mapping info in inode will be inconsistent with SIT table, so in f2fs_fallocate(), it will cause panic when updating SIT with invalid blkaddr. Let's fix the issue by adding sanity check on block address before updating SIT table with it. Cc: stable@vger.kernel.org Reported-by: Ming Yan <yanming@tju.edu.cn> Signed-off-by: Chao Yu <chao.yu@oppo.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Lines changed: 12 additions & 4 deletions

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fs/f2fs/file.c

Lines changed: 12 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1438,11 +1438,19 @@ static int f2fs_do_zero_range(struct dnode_of_data *dn, pgoff_t start,
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ret = -ENOSPC;
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break;
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}
1441-
if (dn->data_blkaddr != NEW_ADDR) {
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f2fs_invalidate_blocks(sbi, dn->data_blkaddr);
1443-
dn->data_blkaddr = NEW_ADDR;
1444-
f2fs_set_data_blkaddr(dn);
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if (dn->data_blkaddr == NEW_ADDR)
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continue;
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1445+
if (!f2fs_is_valid_blkaddr(sbi, dn->data_blkaddr,
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DATA_GENERIC_ENHANCE)) {
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ret = -EFSCORRUPTED;
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break;
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}
1450+
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f2fs_invalidate_blocks(sbi, dn->data_blkaddr);
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dn->data_blkaddr = NEW_ADDR;
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f2fs_set_data_blkaddr(dn);
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}
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f2fs_update_extent_cache_range(dn, start, 0, index - start);

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