"value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnilfs2: fix null-ptr-deref in block_touch_buffer tracepoint\n\nPatch series \"nilfs2: fix null-ptr-deref bugs on block tracepoints\".\n\nThis series fixes null pointer dereference bugs that occur when using\nnilfs2 and two block-related tracepoints.\n\n\nThis patch (of 2):\n\nIt has been reported that when using \"block:block_touch_buffer\"\ntracepoint, touch_buffer() called from __nilfs_get_folio_block() causes a\nNULL pointer dereference, or a general protection fault when KASAN is\nenabled.\n\nThis happens because since the tracepoint was added in touch_buffer(), it\nreferences the dev_t member bh->b_bdev->bd_dev regardless of whether the\nbuffer head has a pointer to a block_device structure. In the current\nimplementation, the block_device structure is set after the function\nreturns to the caller.\n\nHere, touch_buffer() is used to mark the folio/page that owns the buffer\nhead as accessed, but the common search helper for folio/page used by the\ncaller function was optimized to mark the folio/page as accessed when it\nwas reimplemented a long time ago, eliminating the need to call\ntouch_buffer() here in the first place.\n\nSo this solves the issue by eliminating the touch_buffer() call itself."
