In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
nfsd: sample writeback error cursor before async COPY loop<\/p>\n
_nfsd_copy_file_range() samples dst->f_wb_err into “since”
\nafter the copy loop, then uses it to detect writeback errors
\nvia filemap_check_wb_err() once vfs_fsync_range() returns.
\nBecause the nfsd_file cache reuses a single struct file
\nacross requests targeting the same inode, a concurrent
\nCOMMIT or stable WRITE on dst advances dst->f_wb_err to the
\ncurrent mapping->wb_err via file_check_and_advance_wb_err()
\nduring its own vfs_fsync_range(). If that advancement lands
\nbetween the writeback error appearing in mapping->wb_err
\nand the COPY worker sampling “since”, the worker captures
\nthe already-advanced cursor, errseq_check() sees cur ==
\nsince and returns zero, and NFSD4_COPY_F_COMMITTED is set
\neven though writeback failed. CB_OFFLOAD then encodes
\nwr_stable_how = FILE_SYNC4, the client treats the copied
\ndata as durable, and the failure becomes silent data loss.<\/p>\n
Sample since once at the start of the function. The cursor
\nthen reflects state in effect before this COPY issues any
\nwrites, and filemap_check_wb_err() detects any error that
\noccurs during the copy regardless of which thread first
\nobserves it. This matches the pattern used by
\nnfsd_vfs_write() and nfsd4_clone_file_range().<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
nfsd: sample writeback error cursor before async COPY loop<\/p>\n
_nfsd_copy_file_range() samples dst->f_wb_err into “since”
\nafter the co<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-21626","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/21626","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=21626"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21626"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21626"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}