1Description: [CVE-2021-26937] Fix out of bounds array access 2Author: Michael Schröder <mls@suse.de> 3Bug-Debian: https://bugs.debian.org/982435 4Bug: https://savannah.gnu.org/bugs/?60030 5Bug: https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html 6Bug-OSS-Security: https://www.openwall.com/lists/oss-security/2021/02/09/3 7Origin: https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00010.html 8 9Downloaded from Debian: 10https://sources.debian.org/data/main/s/screen/4.8.0-5/debian/patches/99_CVE-2021-26937.patch 11 12Signed-off-by: Peter Korsgaard <peter@korsgaard.com> 13--- a/encoding.c 14+++ b/encoding.c 15@@ -43,7 +43,7 @@ 16 # ifdef UTF8 17 static int recode_char __P((int, int, int)); 18 static int recode_char_to_encoding __P((int, int)); 19-static void comb_tofront __P((int, int)); 20+static void comb_tofront __P((int)); 21 # ifdef DW_CHARS 22 static int recode_char_dw __P((int, int *, int, int)); 23 static int recode_char_dw_to_encoding __P((int, int *, int)); 24@@ -1263,6 +1263,8 @@ 25 {0x30000, 0x3FFFD}, 26 }; 27 28+ if (c >= 0xdf00 && c <= 0xdfff) 29+ return 1; /* dw combining sequence */ 30 return ((bisearch(c, wide, sizeof(wide) / sizeof(struct interval) - 1)) || 31 (cjkwidth && 32 bisearch(c, ambiguous, 33@@ -1330,11 +1332,12 @@ 34 } 35 36 static void 37-comb_tofront(root, i) 38-int root, i; 39+comb_tofront(i) 40+int i; 41 { 42 for (;;) 43 { 44+ int root = i >= 0x700 ? 0x801 : 0x800; 45 debug1("bring to front: %x\n", i); 46 combchars[combchars[i]->prev]->next = combchars[i]->next; 47 combchars[combchars[i]->next]->prev = combchars[i]->prev; 48@@ -1396,9 +1399,9 @@ 49 { 50 /* full, recycle old entry */ 51 if (c1 >= 0xd800 && c1 < 0xe000) 52- comb_tofront(root, c1 - 0xd800); 53+ comb_tofront(c1 - 0xd800); 54 i = combchars[root]->prev; 55- if (c1 == i + 0xd800) 56+ if (i == 0x800 || i == 0x801 || c1 == i + 0xd800) 57 { 58 /* completely full, can't recycle */ 59 debug("utf8_handle_comp: completely full!\n"); 60@@ -1422,7 +1425,7 @@ 61 mc->font = (i >> 8) + 0xd8; 62 mc->fontx = 0; 63 debug3("combinig char %x %x -> %x\n", c1, c, i + 0xd800); 64- comb_tofront(root, i); 65+ comb_tofront(i); 66 } 67 68 #else /* !UTF8 */ 69