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- Description: [CVE-2021-26937] Fix out of bounds array access
- Author: Michael Schröder <mls@suse.de>
- Bug-Debian: https://bugs.debian.org/982435
- Bug: https://savannah.gnu.org/bugs/?60030
- Bug: https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html
- Bug-OSS-Security: https://www.openwall.com/lists/oss-security/2021/02/09/3
- Origin: https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00010.html
-
- --- a/encoding.c
- +++ b/encoding.c
- @@ -43,7 +43,7 @@ static int encmatch __P((char *, char *
- # ifdef UTF8
- static int recode_char __P((int, int, int));
- static int recode_char_to_encoding __P((int, int));
- -static void comb_tofront __P((int, int));
- +static void comb_tofront __P((int));
- # ifdef DW_CHARS
- static int recode_char_dw __P((int, int *, int, int));
- static int recode_char_dw_to_encoding __P((int, int *, int));
- @@ -1263,6 +1263,8 @@ int c;
- {0x30000, 0x3FFFD},
- };
-
- + if (c >= 0xdf00 && c <= 0xdfff)
- + return 1; /* dw combining sequence */
- return ((bisearch(c, wide, sizeof(wide) / sizeof(struct interval) - 1)) ||
- (cjkwidth &&
- bisearch(c, ambiguous,
- @@ -1330,11 +1332,12 @@ int c;
- }
-
- static void
- -comb_tofront(root, i)
- -int root, i;
- +comb_tofront(i)
- +int i;
- {
- for (;;)
- {
- + int root = i >= 0x700 ? 0x801 : 0x800;
- debug1("bring to front: %x\n", i);
- combchars[combchars[i]->prev]->next = combchars[i]->next;
- combchars[combchars[i]->next]->prev = combchars[i]->prev;
- @@ -1396,9 +1399,9 @@ struct mchar *mc;
- {
- /* full, recycle old entry */
- if (c1 >= 0xd800 && c1 < 0xe000)
- - comb_tofront(root, c1 - 0xd800);
- + comb_tofront(c1 - 0xd800);
- i = combchars[root]->prev;
- - if (c1 == i + 0xd800)
- + if (i == 0x800 || i == 0x801 || c1 == i + 0xd800)
- {
- /* completely full, can't recycle */
- debug("utf8_handle_comp: completely full!\n");
- @@ -1422,7 +1425,7 @@ struct mchar *mc;
- mc->font = (i >> 8) + 0xd8;
- mc->fontx = 0;
- debug3("combinig char %x %x -> %x\n", c1, c, i + 0xd800);
- - comb_tofront(root, i);
- + comb_tofront(i);
- }
-
- #else /* !UTF8 */
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