|
@@ -0,0 +1,73 @@
|
|
|
+From a4d3fbdff1e3ca8f87642af2ac8752c30c617a3e Mon Sep 17 00:00:00 2001
|
|
|
+From: Peter Jones <pjones@redhat.com>
|
|
|
+Date: Wed, 15 Apr 2020 15:45:02 -0400
|
|
|
+Subject: yylex: Make lexer fatal errors actually be fatal
|
|
|
+
|
|
|
+When presented with a command that can't be tokenized to anything
|
|
|
+smaller than YYLMAX characters, the parser calls YY_FATAL_ERROR(errmsg),
|
|
|
+expecting that will stop further processing, as such:
|
|
|
+
|
|
|
+ #define YY_DO_BEFORE_ACTION \
|
|
|
+ yyg->yytext_ptr = yy_bp; \
|
|
|
+ yyleng = (int) (yy_cp - yy_bp); \
|
|
|
+ yyg->yy_hold_char = *yy_cp; \
|
|
|
+ *yy_cp = '\0'; \
|
|
|
+ if ( yyleng >= YYLMAX ) \
|
|
|
+ YY_FATAL_ERROR( "token too large, exceeds YYLMAX" ); \
|
|
|
+ yy_flex_strncpy( yytext, yyg->yytext_ptr, yyleng + 1 , yyscanner); \
|
|
|
+ yyg->yy_c_buf_p = yy_cp;
|
|
|
+
|
|
|
+The code flex generates expects that YY_FATAL_ERROR() will either return
|
|
|
+for it or do some form of longjmp(), or handle the error in some way at
|
|
|
+least, and so the strncpy() call isn't in an "else" clause, and thus if
|
|
|
+YY_FATAL_ERROR() is *not* actually fatal, it does the call with the
|
|
|
+questionable limit, and predictable results ensue.
|
|
|
+
|
|
|
+Unfortunately, our implementation of YY_FATAL_ERROR() is:
|
|
|
+
|
|
|
+ #define YY_FATAL_ERROR(msg) \
|
|
|
+ do { \
|
|
|
+ grub_printf (_("fatal error: %s\n"), _(msg)); \
|
|
|
+ } while (0)
|
|
|
+
|
|
|
+The same pattern exists in yyless(), and similar problems exist in users
|
|
|
+of YY_INPUT(), several places in the main parsing loop,
|
|
|
+yy_get_next_buffer(), yy_load_buffer_state(), yyensure_buffer_stack,
|
|
|
+yy_scan_buffer(), etc.
|
|
|
+
|
|
|
+All of these callers expect YY_FATAL_ERROR() to actually be fatal, and
|
|
|
+the things they do if it returns after calling it are wildly unsafe.
|
|
|
+
|
|
|
+Fixes: CVE-2020-10713
|
|
|
+
|
|
|
+Signed-off-by: Peter Jones <pjones@redhat.com>
|
|
|
+Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
|
|
|
+
|
|
|
+Upstream-Status: Backport [https://git.savannah.gnu.org/cgit/grub.git/commit/?id=a4d3fbdff1e3ca8f87642af2ac8752c30c617a3e]
|
|
|
+CVE: CVE-2020-10713
|
|
|
+Signed-off-by: Chee Yang Lee <chee.yang.lee@intel.com>
|
|
|
+---
|
|
|
+ grub-core/script/yylex.l | 4 ++--
|
|
|
+ 1 file changed, 2 insertions(+), 2 deletions(-)
|
|
|
+
|
|
|
+diff --git a/grub-core/script/yylex.l b/grub-core/script/yylex.l
|
|
|
+index 7b44c37b7..b7203c823 100644
|
|
|
+--- a/grub-core/script/yylex.l
|
|
|
++++ b/grub-core/script/yylex.l
|
|
|
+@@ -37,11 +37,11 @@
|
|
|
+
|
|
|
+ /*
|
|
|
+ * As we don't have access to yyscanner, we cannot do much except to
|
|
|
+- * print the fatal error.
|
|
|
++ * print the fatal error and exit.
|
|
|
+ */
|
|
|
+ #define YY_FATAL_ERROR(msg) \
|
|
|
+ do { \
|
|
|
+- grub_printf (_("fatal error: %s\n"), _(msg)); \
|
|
|
++ grub_fatal (_("fatal error: %s\n"), _(msg));\
|
|
|
+ } while (0)
|
|
|
+
|
|
|
+ #define COPY(str, hint) \
|
|
|
+--
|
|
|
+cgit v1.2.1
|
|
|
+
|