In lzfse 1.0, built with gcc 7.2.0 -O3 -flto : <div class="snippet-clipboard-conte

This happens on Ubuntu 14.04.5 ; your eff code prints <div class="snippet-clipboar

Crash (double free) when compressing empty file or pipe about lzfse HOT 3 OPEN

lzfse commented on July 19, 2024

Crash (double free) when compressing empty file or pipe

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Comments (3)

Artoria2e5 commented on July 19, 2024 1

Looks like everything succeeded! Guess it's just the "let's double zero" logical error then.

(The two successes does suggest that it's getting NULL on zero-size allocs, which isn't exactly good for other reasons.)

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Artoria2e5 commented on July 19, 2024

Is this the classic malloc(0) problem ubiquitous on a bunch of systems? Would you like to:

include the operating system in the report

Run a simple snippet to eff with the system:

#include <stdlib.h>
#define STRINGIFY(x) #x
#define TOSTRING(x) STRINGIFY(x)
#define PEE_ERR(P, S) if(!(P)) perror(S ":" TOSTRING(__LINE__))
int main(void) {
  void* p = malloc(0);
  PEE_ERR(p, "malloc");
  p = realloc(p, 0);
  PEE_ERR(p, "realloc");
  free(p);
  perror("free");
  return 0;
}

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RJVB commented on July 19, 2024

This happens on Ubuntu 14.04.5 ; your eff code prints

eff.c: In function ‘main’:
eff.c:4:32: warning: implicit declaration of function ‘perror’ [-Wimplicit-function-declaration]
 #define PEE_ERR(P, S) if(!(P)) perror(S ":" TOSTRING(__LINE__))
                                ^
eff.c:7:3: note: in expansion of macro ‘PEE_ERR’
   PEE_ERR(p, "malloc");
   ^~~~~~~
realloc:9: Success
free: Success

When I test on Mac OS X (10.9.5) the encoder ends up in an endless loop:

LZFSE encode
Input: empty.diff
Output: stdout
Input size: 0 B
Output buffer was too small, increasing size...
Output buffer was too small, increasing size...
Output buffer was too small, increasing size...
Output buffer was too small, increasing size...
Output buffer was too small, increasing size...
Output buffer was too small, increasing size...

and the eff code prints

eff.c:7:3: warning: implicit declaration of function 'perror' is invalid in C99 [-Wimplicit-function-declaration]
  PEE_ERR(p, "malloc");
  ^
eff.c:4:32: note: expanded from macro 'PEE_ERR'
#define PEE_ERR(P, S) if(!(P)) perror(S ":" TOSTRING(__LINE__))
                               ^
1 warning generated.
free: Undefined error: 0

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