Merge tag 'hardening-v7.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening updates from Kees Cook:

 - Provide kmalloc_obj*-style API for devm_kmalloc()

 - Improve seq_buf API for saner C String handling with several bug
   fixes along the way (Kees Cook, Bill Wendling)

 - Overflow helper readability improvements (Bill Wendling)

 - Unexport native_write_cr4() (Dennis Chen)

 - um: fix CONFIG_GCOV for built-in code (Johannes Berg)

 - Improve stackinit test coverage (Justin Stitt)

 - KMSAN: fix memset() when using fortify-source, again (Arnd Bergmann)

 - lkdtm: use kmalloc() instead of __get_free_page (Mahad Ibrahim)

 - signalfd: don't dequeue the forced fatal signals (Oleg Nesterov)

 - Fix randstruct to recognize new container_of() behavior

 - coccinelle: kmalloc_obj: Convert multi-byte integral allocations too

 - Fix a couple remaining allocation return type mismatches

* tag 'hardening-v7.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (29 commits)
  overflow: Match arithmetic in both parts of __builtin_choose_expr
  lkdtm: Make UNSET_SMEP built-in-only and unexport native_write_cr4()
  extcon: realtek: Remove const from type_c_cfg allocation type
  coresight: cti: Add const to con_groups allocation type
  docs: core-api: Document the seq_buf API
  nvdimm: ndtest: Return the string length from flags_show()
  powerpc/papr_scm: Return the string length from the sysfs show functions
  seq_buf: Add seq_buf_init_append()
  bpf: Remove dead newline stripping from format_disasm_line()
  seq_buf: Add seq_buf_terminate()
  seq_buf: Add seq_buf_strlen()
  seq_buf: Clear what a writer did not claim when a seq_buf overflows
  seq_buf: Copy what fits when seq_buf_puts() and seq_buf_putmem() overflow
  scsi: lpfc: Print rx monitor records straight into the seq_buf
  seq_buf: Do not pop from an overflowed seq_buf
  seq_buf: Do not print an empty line from an overflowed seq_buf_do_printk()
  .get_maintainer.ignore: Add Kees Cook
  devres: Provide kmalloc_obj*-style API for devm_kmalloc
  mm: Move default_gfp() into gfp_types.h
  kunit/stackinit: Clean up XFAIL under instrumentation
  ...

1 files changed, 28 insertions, 9 deletions

diff --git a/lib/seq_buf.c b/lib/seq_buf.c
index a92093f346da..54b76044e4ba 100644
--- a/lib/seq_buf.c
+++ b/lib/seq_buf.c
@@ -76,6 +76,8 @@ int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
 			s->len += len;
 			return 0;
 		}
+		/* vsnprintf() wrote as much as fits, so none of it is stale */
+		s->len = s->size;
 	}
 	seq_buf_set_overflow(s);
 	return -1;
@@ -128,7 +130,7 @@ void seq_buf_do_printk(struct seq_buf *s, const char *lvl)
 	}
 
 	/* No trailing LF */
-	if (start < s->buffer + s->len)
+	if (*start)
 		printk("%s%s\n", lvl, start);
 }
 EXPORT_SYMBOL_GPL(seq_buf_do_printk);
@@ -164,6 +166,8 @@ int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
 			s->len += ret;
 			return 0;
 		}
+		/* bstr_printf() wrote as much as fits, so none of it is stale */
+		s->len = s->size;
 	}
 	seq_buf_set_overflow(s);
 	return -1;
@@ -175,7 +179,9 @@ int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
  * @s: seq_buf descriptor
  * @str: simple string to record
  *
- * Copy a simple string into the sequence buffer.
+ * Copy a simple string into the sequence buffer. If @str does not fit,
+ * as much of it as fits is copied, followed by a null byte, as
+ * seq_buf_printf() does.
  *
  * Returns: zero on success, -1 on overflow.
  */
@@ -194,6 +200,11 @@ int seq_buf_puts(struct seq_buf *s, const char *str)
 		s->len += len - 1;
 		return 0;
 	}
+	/* Copy what fits, so the buffer never holds stale bytes */
+	if (s->len < s->size) {
+		strscpy(s->buffer + s->len, str, s->size - s->len);
+		s->len = s->size;
+	}
 	seq_buf_set_overflow(s);
 	return -1;
 }
@@ -229,7 +240,7 @@ EXPORT_SYMBOL_GPL(seq_buf_putc);
  *
  * There may be cases where raw memory needs to be written into the
  * buffer and a strcpy() would not work. Using this function allows
- * for such cases.
+ * for such cases. If @mem does not fit, as much of it as fits is copied.
  *
  * Returns: zero on success, -1 on overflow.
  */
@@ -242,9 +253,15 @@ int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
 		s->len += len;
 		return 0;
 	}
+	/* Copy what fits, so the buffer never holds stale bytes */
+	if (s->len < s->size) {
+		memcpy(s->buffer + s->len, mem, s->size - s->len);
+		s->len = s->size;
+	}
 	seq_buf_set_overflow(s);
 	return -1;
 }
+EXPORT_SYMBOL_GPL(seq_buf_putmem);
 
 #define MAX_MEMHEX_BYTES	8U
 #define HEX_CHARS		(MAX_MEMHEX_BYTES*2 + 1)
@@ -330,6 +347,7 @@ int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
 
 	return res;
 }
+EXPORT_SYMBOL_GPL(seq_buf_path);
 
 /**
  * seq_buf_to_user - copy the sequence buffer to user space
@@ -391,12 +409,13 @@ int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, size_t start, int cnt)
  *
  * Function is an analogue of print_hex_dump() and thus has similar interface.
  *
- * linebuf size is maximal length for one line.
- * 32 * 3 - maximum bytes per line, each printed into 2 chars + 1 for
- *	separating space
- * 2 - spaces separating hex dump and ASCII representation
- * 32 - ASCII representation
- * 1 - terminating '\0'
+ * linebuf size is maximal length for one line::
+ *
+ *	32 * 3 - maximum bytes per line, each printed into 2 chars + 1 for
+ *		 separating space
+ *	2 - spaces separating hex dump and ASCII representation
+ *	32 - ASCII representation
+ *	1 - terminating '\0'
  *
  * Returns: zero on success, -1 on overflow.
  */