AcoSail/kernel_optimize_test
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Input: gtco - bounds check collection indent level

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The GTCO tablet input driver configures itself from an HID report sent
via USB during the initial enumeration process. Some debugging messages
are generated during the parsing. A debugging message indentation
counter is not bounds checked, leading to the ability for a specially
crafted HID report to cause '-' and null bytes be written past the end
of the indentation array. As long as the kernel has CONFIG_DYNAMIC_DEBUG
enabled, this code will not be optimized out.  This was discovered
during code review after a previous syzkaller bug was found in this
driver.

Signed-off-by: Grant Hernandez <granthernandez@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Grant Hernandez 2019-07-13 01:00:12 -07:00 committed by Dmitry Torokhov
parent cc95527cce
commit 2a017fd82c
1 changed files with 17 additions and 3 deletions
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20
drivers/input/tablet/gtco.c
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@ -78,6 +78,7 @@ Scott Hill shill@gtcocalcomp.com
/* Max size of a single report */
#define REPORT_MAX_SIZE 10
#define MAX_COLLECTION_LEVELS 10
/* Bitmask whether pen is in range */
@ -223,8 +224,7 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report,
char maintype = 'x';
char globtype[12];
int indent = 0;
char indentstr[10] = "";
char indentstr[MAX_COLLECTION_LEVELS + 1] = { 0 };
dev_dbg(ddev, "======>>>>>>PARSE<<<<<<======\n");
@ -350,6 +350,13 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report,
case TAG_MAIN_COL_START:
maintype = 'S';
if (indent == MAX_COLLECTION_LEVELS) {
dev_err(ddev, "Collection level %d would exceed limit of %d\n",
indent + 1,
MAX_COLLECTION_LEVELS);
break;
}
if (data == 0) {
dev_dbg(ddev, "======>>>>>> Physical\n");
strcpy(globtype, "Physical");
@ -369,8 +376,15 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report,
break;
case TAG_MAIN_COL_END:
dev_dbg(ddev, "<<<<<<======\n");
maintype = 'E';
if (indent == 0) {
dev_err(ddev, "Collection level already at zero\n");
break;
}
dev_dbg(ddev, "<<<<<<======\n");
indent--;
for (x = 0; x < indent; x++)
indentstr[x] = '-';