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CVE-2021-47460

ocfs2: fix data corruption after conversion from inline format PUBLISHED

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix data corruption after conversion from inline format Commit 6dbf7bb55598 ("fs: Don't invalidate page buffers in block_write_full_page()") uncovered a latent bug in ocfs2 conversion from inline inode format to a normal inode format. The code in ocfs2_convert_inline_data_to_extents() attempts to zero out the whole cluster allocated for file data by grabbing, zeroing, and dirtying all pages covering this cluster. However these pages are beyond i_size, thus writeback code generally ignores these dirty pages and no blocks were ever actually zeroed on the disk. This oversight was fixed by commit 693c241a5f6a ("ocfs2: No need to zero pages past i_size.") for standard ocfs2 write path, inline conversion path was apparently forgotten; the commit log also has a reasoning why the zeroing actually is not needed. After commit 6dbf7bb55598, things became worse as writeback code stopped invalidating buffers on pages beyond i_size and thus these pages end up with clean PageDirty bit but with buffers attached to these pages being still dirty. So when a file is converted from inline format, then writeback triggers, and then the file is grown so that these pages become valid, the invalid dirtiness state is preserved, mark_buffer_dirty() does nothing on these pages (buffers are already dirty) but page is never written back because it is clean. So data written to these pages is lost once pages are reclaimed. Simple reproducer for the problem is: xfs_io -f -c "pwrite 0 2000" -c "pwrite 2000 2000" -c "fsync" \ -c "pwrite 4000 2000" ocfs2_file After unmounting and mounting the fs again, you can observe that end of 'ocfs2_file' has lost its contents. Fix the problem by not doing the pointless zeroing during conversion from inline format similarly as in the standard write path. [akpm@linux-foundation.org: fix whitespace, per Joseph]

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected acef5107e2eacb08a16ad5db60320d65bd26a6c0 before 560edd14de2bf9dbc0129681eeb4d5ef87cc105f; affected 7ed80e77c908cbaa686529a49f8ae0060c5caee7 before 8e6bfb4f70168ddfd32fb6dc028ad52faaf1f32e; affected 7ce2b16bad2cbfa3fa7bbc42c4448914f639ca47 before a3a089c241cd49b33a8cdd7fcb37cc87a086912a; affected f8a6a2ed4b7d1c3c8631eeb6d00572bc853094a8 before b05caf023b14cbed9223bb5b48ecc7bffe38f632; affected 6dbf7bb555981fb5faf7b691e8f6169fc2b2e63b before f1b98569e81c37d7e0deada7172f8f60860c1360; affected 6dbf7bb555981fb5faf7b691e8f6169fc2b2e63b before fa9b6b6c953e3f6441ed6cf83b4c771dac2dae08; affected 6dbf7bb555981fb5faf7b691e8f6169fc2b2e63b before 5314454ea3ff6fc746eaf71b9a7ceebed52888fa; affected 36ed9e604215f58cec0381ca5fcc6da05f2d87ca; affected 4.9.242 before 4.9.288; affected 4.14.204 before 4.14.253; affected 4.19.155 before 4.19.214; affected 5.4.75 before 5.4.156; affected 5.9.5 before 5.10
Linux / Linuxaffected 5.10; unaffected 0 before 5.10; unaffected 4.9.288 through 4.9.*; unaffected 4.14.253 through 4.14.*; unaffected 4.19.214 through 4.19.*; unaffected 5.4.156 through 5.4.*; unaffected 5.10.76 through 5.10.*; unaffected 5.14.15 through 5.14.*; unaffected 5.15 through *

CWE

No CWE identifiers supplied.

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

CVE

No English description supplied.