In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix null-ptr-deref in blocktouchbuffer tracepoint Patch series "nilfs2: fix null-ptr-deref bugs on block tracepoints". This series fixes null pointer dereference bugs that occur when using nilfs2 and two block-related tracepoints. This patch (of 2): It has been reported that when using "block:blocktouchbuffer" tracepoint, touchbuffer() called from _nilfsgetfolioblock() causes a NULL pointer dereference, or a general protection fault when KASAN is enabled. This happens because since the tracepoint was added in touchbuffer(), it references the devt member bh->bbdev->bddev regardless of whether the buffer head has a pointer to a blockdevice structure. In the current implementation, the blockdevice structure is set after the function returns to the caller. Here, touchbuffer() is used to mark the folio/page that owns the buffer head as accessed, but the common search helper for folio/page used by the caller function was optimized to mark the folio/page as accessed when it was reimplemented a long time ago, eliminating the need to call touchbuffer() here in the first place. So this solves the issue by eliminating the touchbuffer() call itself.