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sscanf 1 byte hex data without overflow


sscanf 1 byte hex data without overflow

By : dimnikolov
Date : November 22 2020, 10:48 AM
it helps some times You want to use %02hhX on an array of unsigned char. (So uint8_t is fine)
code :


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Is the sscanf function in the Linux kernel susceptible to buffer overflow attacks?

Is the sscanf function in the Linux kernel susceptible to buffer overflow attacks?


By : cymond
Date : March 29 2020, 07:55 AM
Any of those help The Linux sscanf() is vulnerable to buffer overflows; inspection of the source shows this. You can use width specifiers to limit the amount a %s is allowed to write. At some point your str must have had copy_from_user() run on it as well. It is possible the the user space to pass some garbage pointer to the kernel.
In the version of Linux you cited, the scsi_sysfs.c does have a buffer overflow. The latest version does not. The committed fix should fix the issue you see.
sscanf specifier %[] and buffer overflow

sscanf specifier %[] and buffer overflow


By : Manish Anand
Date : March 29 2020, 07:55 AM
hope this fix your issue sorry for this "another" sscanf question but I cannot find any solution by experimenting. , This task is much easier using strtok_r
code :
char  r_value[5];
char  p_value[6];
char *token;
char *saveptr;

token = strtok_r(str, ":", &saveptr);
if (token == NULL)
    return; /* there is no ":" in the string so handle failure properly */
token = strtok_r(NULL, ":", &saveptr);
if (token == NULL)
    return; /* no more tokens found so handle failure properly */
strncpy(r_value, token, sizeof r_value);
r_value[sizeof(r_value) - 1] = '\0';
token = strtok_r(NULL, ":", &saveptr);
if (token == NULL)
    return; /* no more tokens found so handle failure properly */
strncpy(p_value, token, sizeof p_value);
p_value[sizeof(p_value) - 1] = '\0';
char *str = "tag:R123:P1234";
char *str = strdup("tag:R123:P1234");
Zeroing of the last byte with sscanf() on Arduino

Zeroing of the last byte with sscanf() on Arduino


By : liuyc_
Date : March 29 2020, 07:55 AM
like below fixes the issue Here is a strange issue with Arduino function sscanf(). It zeroes the last byte of scanned integer value (int, long) if 1-byte value (bool, byte, char) follows it. , It's Illegal:
code :
 sscanf(buf, "%x", /* byte*/ &val ) 
int someInt, wrkInt;
byte someByte;

void setup() {
  Serial.begin(9600);

  sscanf("10000 10", "%d %d", &someInt, &wrkInt);  // %X too, rule is the same
  someByte = wrkInt;
...
}
Possible overflow on sscanf

Possible overflow on sscanf


By : Florin Medrea
Date : March 29 2020, 07:55 AM
This might help you Generally speaking:
When trying to write portable code, the format specifier for an int64_t can be different on different platforms. An int64_t might be a typedef for a number of types, including int, long or long long.
Is there a version of sscanf() that doesn't start from the first byte?

Is there a version of sscanf() that doesn't start from the first byte?


By : Teena
Date : March 29 2020, 07:55 AM
Any of those help In C, fscanf() doesn't necessarily read a file from its first byte; It reads the file from its current access position. I need a version of sscanf() that does the same with strings. Is there any function (standard or non-standard) for this purpose? , In simple cases, you can use the "%n" specifier for that, like this
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