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staging: unisys: visorbus: address theoretical int overflows
Add necessary casting to several places where we were doing 32-bit arithmetic (unsigned) to produce a 64-bit (unsigned long) result, to prevent the theoretical possibility of a 32-bit overflow during the arithmetic. FYI, these are unsigned long: ctx->param_bytes ctx->allocbytes These are unsigned int: bytes phdr->name_offset phdr->name_length Here is the test program demonstrating why we really need the casts: void main() { unsigned int i; unsigned long il; printf("sizeof(int) =%dn",sizeof(i)); printf("sizeof(long)=%dn",sizeof(il)); i = (unsigned int)((((unsigned long)(1)) << 32) - 1); printf("i = %un", i); il = i+1; printf("adding 1 withOUT cast = %lun", il); il = (unsigned long)i+1; printf("adding 1 WITH cast = %lun", il); } [selltc@mac tmp]$ gcc x.c -o x.out [selltc@mac tmp]$ ./x.out sizeof(int) =4 sizeof(long)=8 i = 4294967295 adding 1 withOUT cast = 0 adding 1 WITH cast = 4294967296 Signed-off-by: Tim Sell <Timothy.Sell@unisys.com> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: David Kershner <david.kershner@unisys.com> Reviewed-by: David Binder <david.binder@unisys.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1c0c275b11
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1 changed files with 4 additions and 3 deletions
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@ -581,7 +581,8 @@ static void *parser_name_get(struct parser_context *ctx)
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struct visor_controlvm_parameters_header *phdr;
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phdr = &ctx->data;
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if (phdr->name_offset + phdr->name_length > ctx->param_bytes)
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if ((unsigned long)phdr->name_offset +
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(unsigned long)phdr->name_length > ctx->param_bytes)
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return NULL;
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ctx->curr = (char *)&phdr + phdr->name_offset;
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ctx->bytes_remaining = phdr->name_length;
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@ -1308,13 +1309,13 @@ static void parser_done(struct parser_context *ctx)
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static struct parser_context *parser_init_stream(u64 addr, u32 bytes,
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bool *retry)
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{
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int allocbytes;
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unsigned long allocbytes;
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struct parser_context *ctx;
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void *mapping;
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*retry = false;
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/* alloc an extra byte to ensure payload is \0 terminated */
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allocbytes = bytes + 1 + (sizeof(struct parser_context) -
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allocbytes = (unsigned long)bytes + 1 + (sizeof(struct parser_context) -
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sizeof(struct visor_controlvm_parameters_header));
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if ((chipset_dev->controlvm_payload_bytes_buffered + bytes) >
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MAX_CONTROLVM_PAYLOAD_BYTES) {
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