6ca1a7c277
encoding.c in GNU Screen through 4.8.0 allows remote attackers to cause a denial of service (invalid write access and application crash) or possibly have unspecified other impact via a crafted UTF-8 character sequence. For more details, see the oss-security discussion: https://www.openwall.com/lists/oss-security/2021/02/09/3 So far no fix has been added to upstream git, and a number of early proposed fixes caused regressions, so pull the security fix from the screen 4.8.0-5 Debian package. Signed-off-by: Peter Korsgaard <peter@korsgaard.com> Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
69 lines
2.2 KiB
Diff
69 lines
2.2 KiB
Diff
Description: [CVE-2021-26937] Fix out of bounds array access
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Author: Michael Schröder <mls@suse.de>
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Bug-Debian: https://bugs.debian.org/982435
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Bug: https://savannah.gnu.org/bugs/?60030
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Bug: https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html
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Bug-OSS-Security: https://www.openwall.com/lists/oss-security/2021/02/09/3
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Origin: https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00010.html
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Downloaded from Debian:
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https://sources.debian.org/data/main/s/screen/4.8.0-5/debian/patches/99_CVE-2021-26937.patch
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Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
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--- a/encoding.c
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+++ b/encoding.c
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@@ -43,7 +43,7 @@
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# ifdef UTF8
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static int recode_char __P((int, int, int));
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static int recode_char_to_encoding __P((int, int));
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-static void comb_tofront __P((int, int));
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+static void comb_tofront __P((int));
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# ifdef DW_CHARS
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static int recode_char_dw __P((int, int *, int, int));
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static int recode_char_dw_to_encoding __P((int, int *, int));
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@@ -1263,6 +1263,8 @@
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{0x30000, 0x3FFFD},
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};
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+ if (c >= 0xdf00 && c <= 0xdfff)
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+ return 1; /* dw combining sequence */
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return ((bisearch(c, wide, sizeof(wide) / sizeof(struct interval) - 1)) ||
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(cjkwidth &&
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bisearch(c, ambiguous,
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@@ -1330,11 +1332,12 @@
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}
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static void
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-comb_tofront(root, i)
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-int root, i;
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+comb_tofront(i)
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+int i;
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{
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for (;;)
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{
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+ int root = i >= 0x700 ? 0x801 : 0x800;
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debug1("bring to front: %x\n", i);
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combchars[combchars[i]->prev]->next = combchars[i]->next;
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combchars[combchars[i]->next]->prev = combchars[i]->prev;
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@@ -1396,9 +1399,9 @@
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{
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/* full, recycle old entry */
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if (c1 >= 0xd800 && c1 < 0xe000)
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- comb_tofront(root, c1 - 0xd800);
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+ comb_tofront(c1 - 0xd800);
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i = combchars[root]->prev;
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- if (c1 == i + 0xd800)
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+ if (i == 0x800 || i == 0x801 || c1 == i + 0xd800)
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{
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/* completely full, can't recycle */
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debug("utf8_handle_comp: completely full!\n");
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@@ -1422,7 +1425,7 @@
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mc->font = (i >> 8) + 0xd8;
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mc->fontx = 0;
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debug3("combinig char %x %x -> %x\n", c1, c, i + 0xd800);
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- comb_tofront(root, i);
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+ comb_tofront(i);
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}
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#else /* !UTF8 */
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