On 32 bit platform, the bit position of GETBIT/SETBIT/BITFIELD/BITCOUNT,BITPOS may overflow (see CVE-2021-32761) (#9191)

GETBIT, SETBIT may access wrong address because of wrap.
BITCOUNT and BITPOS may return wrapped results.
BITFIELD may access the wrong address but also allocate insufficient memory and segfault (see CVE-2021-32761).

This commit uses `uint64_t` or `long long` instead of `size_t`.
related https://github.com/redis/redis/pull/8096

At 32bit platform:
> setbit bit 4294967295 1
(integer) 0
> config set proto-max-bulk-len 536870913
OK
> append bit "\xFF"
(integer) 536870913
> getbit bit 4294967296
(integer) 0

When the bit index is larger than 4294967295, size_t can't hold bit index. In the past,  `proto-max-bulk-len` is limit to 536870912, so there is no problem.

After this commit, bit position is stored in `uint64_t` or `long long`. So when `proto-max-bulk-len > 536870912`, 32bit platforms can still be correct.

For 64bit platform, this problem still exists. The major reason is bit pos 8 times of byte pos. When proto-max-bulk-len is very larger, bit pos may overflow.
But at 64bit platform, we don't have so long string. So this bug may never happen.

Additionally this commit add a test cost `512MB` memory which is tag as `large-memory`. Make freebsd ci and valgrind ci ignore this test.

.github/workflows/daily.yml

@@ -254,7 +254,7 @@ jobs:
         sudo apt-get install tcl8.6 tclx valgrind -y
     - name: test
       if: true && !contains(github.event.inputs.skiptests, 'redis')
-      run: ./runtest --valgrind --verbose --clients 1 --dump-logs ${{github.event.inputs.test_args}}
+      run: ./runtest --valgrind --verbose --clients 1 --tags -large-memory --dump-logs ${{github.event.inputs.test_args}}
     - name: module api test
       if: true && !contains(github.event.inputs.skiptests, 'modules')
       run: ./runtest-moduleapi --valgrind --no-latency --verbose --clients 1 ${{github.event.inputs.test_args}}
@@ -285,7 +285,7 @@ jobs:
         sudo apt-get install tcl8.6 tclx valgrind -y
     - name: test
       if: true && !contains(github.event.inputs.skiptests, 'redis')
-      run: ./runtest --valgrind --verbose --clients 1 --dump-logs ${{github.event.inputs.test_args}}
+      run: ./runtest --valgrind --verbose --clients 1 --tags -large-memory --dump-logs ${{github.event.inputs.test_args}}
     - name: module api test
       if: true && !contains(github.event.inputs.skiptests, 'modules')
       run: ./runtest-moduleapi --valgrind --no-latency --verbose --clients 1 ${{github.event.inputs.test_args}}
@@ -420,7 +420,7 @@ jobs:
         prepare: pkg install -y bash gmake lang/tcl86 lang/tclx
         run: >
           gmake || exit 1 ;
-          if echo "${{github.event.inputs.skiptests}}" | grep -vq redis ; then ./runtest --accurate --verbose --no-latency --dump-logs ${{github.event.inputs.test_args}} || exit 1 ; fi ;
+          if echo "${{github.event.inputs.skiptests}}" | grep -vq redis ; then ./runtest --accurate --verbose --no-latency --tags -large-memory --dump-logs ${{github.event.inputs.test_args}} || exit 1 ; fi ;
           if echo "${{github.event.inputs.skiptests}}" | grep -vq modules ; then MAKE=gmake ./runtest-moduleapi --verbose ${{github.event.inputs.test_args}} || exit 1 ; fi ;
           if echo "${{github.event.inputs.skiptests}}" | grep -vq sentinel ; then ./runtest-sentinel ${{github.event.inputs.cluster_test_args}} || exit 1 ; fi ;
           if echo "${{github.event.inputs.skiptests}}" | grep -vq cluster ; then ./runtest-cluster ${{github.event.inputs.cluster_test_args}} || exit 1 ; fi ;

src/bitops.c

@@ -37,8 +37,8 @@
 /* Count number of bits set in the binary array pointed by 's' and long
  * 'count' bytes. The implementation of this function is required to
  * work with an input string length up to 512 MB or more (server.proto_max_bulk_len) */
-size_t redisPopcount(void *s, long count) {
-    size_t bits = 0;
+long long redisPopcount(void *s, long count) {
+    long long bits = 0;
     unsigned char *p = s;
     uint32_t *p4;
     static const unsigned char bitsinbyte[256] = {0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,4,5,5,6,5,6,6,7,5,6,6,7,6,7,7,8};
@@ -98,11 +98,11 @@ size_t redisPopcount(void *s, long count) {
  * no zero bit is found, it returns count*8 assuming the string is zero
  * padded on the right. However if 'bit' is 1 it is possible that there is
  * not a single set bit in the bitmap. In this special case -1 is returned. */
-long redisBitpos(void *s, unsigned long count, int bit) {
+long long redisBitpos(void *s, unsigned long count, int bit) {
     unsigned long *l;
     unsigned char *c;
     unsigned long skipval, word = 0, one;
-    long pos = 0; /* Position of bit, to return to the caller. */
+    long long pos = 0; /* Position of bit, to return to the caller. */
     unsigned long j;
     int found;
 
@@ -410,7 +410,7 @@ void printBits(unsigned char *p, unsigned long count) {
  * If the 'hash' argument is true, and 'bits is positive, then the command
  * will also parse bit offsets prefixed by "#". In such a case the offset
  * is multiplied by 'bits'. This is useful for the BITFIELD command. */
-int getBitOffsetFromArgument(client *c, robj *o, size_t *offset, int hash, int bits) {
+int getBitOffsetFromArgument(client *c, robj *o, uint64_t *offset, int hash, int bits) {
     long long loffset;
     char *err = "bit offset is not an integer or out of range";
     char *p = o->ptr;
@@ -435,7 +435,7 @@ int getBitOffsetFromArgument(client *c, robj *o, size_t *offset, int hash, int b
         return C_ERR;
     }
 
-    *offset = (size_t)loffset;
+    *offset = loffset;
     return C_OK;
 }
 
@@ -477,7 +477,7 @@ int getBitfieldTypeFromArgument(client *c, robj *o, int *sign, int *bits) {
  * so that the 'maxbit' bit can be addressed. The object is finally
  * returned. Otherwise if the key holds a wrong type NULL is returned and
  * an error is sent to the client. */
-robj *lookupStringForBitCommand(client *c, size_t maxbit) {
+robj *lookupStringForBitCommand(client *c, uint64_t maxbit) {
     size_t byte = maxbit >> 3;
     robj *o = lookupKeyWrite(c->db,c->argv[1]);
     if (checkType(c,o,OBJ_STRING)) return NULL;
@@ -527,7 +527,7 @@ unsigned char *getObjectReadOnlyString(robj *o, long *len, char *llbuf) {
 void setbitCommand(client *c) {
     robj *o;
     char *err = "bit is not an integer or out of range";
-    size_t bitoffset;
+    uint64_t bitoffset;
     ssize_t byte, bit;
     int byteval, bitval;
     long on;
@@ -566,7 +566,7 @@ void setbitCommand(client *c) {
 void getbitCommand(client *c) {
     robj *o;
     char llbuf[32];
-    size_t bitoffset;
+    uint64_t bitoffset;
     size_t byte, bit;
     size_t bitval = 0;
 
@@ -888,7 +888,7 @@ void bitposCommand(client *c) {
         addReplyLongLong(c, -1);
     } else {
         long bytes = end-start+1;
-        long pos = redisBitpos(p+start,bytes,bit);
+        long long pos = redisBitpos(p+start,bytes,bit);
 
         /* If we are looking for clear bits, and the user specified an exact
          * range with start-end, we can't consider the right of the range as
@@ -897,11 +897,11 @@ void bitposCommand(client *c) {
          * So if redisBitpos() returns the first bit outside the range,
          * we return -1 to the caller, to mean, in the specified range there
          * is not a single "0" bit. */
-        if (end_given && bit == 0 && pos == bytes*8) {
+        if (end_given && bit == 0 && pos == (long long)bytes<<3) {
             addReplyLongLong(c,-1);
             return;
         }
-        if (pos != -1) pos += start*8; /* Adjust for the bytes we skipped. */
+        if (pos != -1) pos += (long long)start<<3; /* Adjust for the bytes we skipped. */
         addReplyLongLong(c,pos);
     }
 }
@@ -933,12 +933,12 @@ struct bitfieldOp {
  * GET subcommand is allowed, other subcommands will return an error. */
 void bitfieldGeneric(client *c, int flags) {
     robj *o;
-    size_t bitoffset;
+    uint64_t bitoffset;
     int j, numops = 0, changes = 0;
     struct bitfieldOp *ops = NULL; /* Array of ops to execute at end. */
     int owtype = BFOVERFLOW_WRAP; /* Overflow type. */
     int readonly = 1;
-    size_t highest_write_offset = 0;
+    uint64_t highest_write_offset = 0;
 
     for (j = 2; j < c->argc; j++) {
         int remargs = c->argc-j-1; /* Remaining args other than current. */
@@ -1128,9 +1128,9 @@ void bitfieldGeneric(client *c, int flags) {
              * object boundaries. */
             memset(buf,0,9);
             int i;
-            size_t byte = thisop->offset >> 3;
+            uint64_t byte = thisop->offset >> 3;
             for (i = 0; i < 9; i++) {
-                if (src == NULL || i+byte >= (size_t)strlen) break;
+                if (src == NULL || i+byte >= (uint64_t)strlen) break;
                 buf[i] = src[i+byte];
             }
 

src/server.h

@@ -1845,7 +1845,7 @@ void getRandomHexChars(char *p, size_t len);
 void getRandomBytes(unsigned char *p, size_t len);
 uint64_t crc64(uint64_t crc, const unsigned char *s, uint64_t l);
 void exitFromChild(int retcode);
-size_t redisPopcount(void *s, long count);
+long long redisPopcount(void *s, long count);
 int redisSetProcTitle(char *title);
 int validateProcTitleTemplate(const char *template);
 int redisCommunicateSystemd(const char *sd_notify_msg);

tests/unit/bitops.tcl

@@ -348,4 +348,30 @@ start_server {tags {"bitops"}} {
             }
         }
     }
+
+    test "BIT pos larger than UINT_MAX" {
+        set bytes [expr (1 << 29) + 1]
+        set bitpos [expr (1 << 32)]
+        set oldval [lindex [r config get proto-max-bulk-len] 1]
+        r config set proto-max-bulk-len $bytes
+        r setbit mykey $bitpos 1
+        assert_equal $bytes [r strlen mykey]
+        assert_equal 1 [r getbit mykey $bitpos]
+        assert_equal [list 128 128 -1] [r bitfield mykey get u8 $bitpos set u8 $bitpos 255 get i8 $bitpos]
+        assert_equal $bitpos [r bitpos mykey 1]
+        assert_equal $bitpos [r bitpos mykey 1 [expr $bytes - 1]]
+        if {$::accurate} {
+            # set all bits to 1
+            set mega [expr (1 << 23)]
+            set part [string repeat "\xFF" $mega]
+            for {set i 0} {$i < 64} {incr i} {
+                r setrange mykey [expr $i * $mega] $part
+            }
+            r setrange mykey [expr $bytes - 1] "\xFF"
+            assert_equal [expr $bitpos + 8] [r bitcount mykey]
+            assert_equal -1 [r bitpos mykey 0 0 [expr $bytes - 1]]
+        }
+        r config set proto-max-bulk-len $oldval
+        r del mykey
+    } {1} {large-memory}
 }