UBIFS error (ubi0:0 pid 1234): ubifs_read_node: bad node type (255 but expected 1) ktag operation not allowed When kernel debugging features are enabled (e.g., CONFIG_KASAN=y or CONFIG_SLUB_DEBUG=y ), the kernel assigns tags to memory objects to detect invalid accesses.
BUG: KASAN: double-free in kfree+0x12/0x180 ktag operation not allowed on object at ffff88800c5e2e00 Some security modules use kernel tags to store security contexts. The setxattr or getxattr system calls may be used to read/write these tags. ktag operation not allowed
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setxattr("file.txt", "security.ktag", ...) = -1 EPERM (Operation not permitted) ktag operation not allowed Proprietary or out-of-tree kernel modules sometimes implement custom tagging for buffer management or debugging. If these modules fail to acquire the proper kernel capabilities or attempt operations in an unsafe context (e.g., interrupt context without proper locking), the kernel may reject the tag operation. Root Causes Analysis The "ktag operation not allowed" error can stem from several underlying root causes. Understanding these is key to effective troubleshooting. UBIFS error (ubi0:0 pid 1234): ubifs_read_node: bad node
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: A process without CAP_MAC_ADMIN or CAP_SYS_ADMIN tries to modify security tags on a file or socket. : setxattr("file
: Performing a read or write operation on a UBIFS volume when the kernel detects that the tag metadata is corrupted, out of sequence, or being accessed by an unauthorized process (e.g., direct block device writes bypassing UBIFS).