debian/patches/security/0001-util-add-slirp_fmt-helpers.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= <marcandre.lureau@redhat.com>
   3 Date: Mon, 27 Jan 2020 10:24:09 +0100
   4 Subject: [PATCH 1/2] util: add slirp_fmt() helpers
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 Various calls to snprintf() in libslirp assume that snprintf() returns
  10 "only" the number of bytes written (excluding terminating NUL).
  11
  12 https://pubs.opengroup.org/onlinepubs/9699919799/functions/snprintf.html#tag_16_159_04
  13
  14 "Upon successful completion, the snprintf() function shall return the
  15 number of bytes that would be written to s had n been sufficiently
  16 large excluding the terminating null byte."
  17
  18 Introduce slirp_fmt() that handles several pathological cases the
  19 way libslirp usually expect:
  20
  21 - treat error as fatal (instead of silently returning -1)
  22
  23 - fmt0() will always \0 end
  24
  25 - return the number of bytes actually written (instead of what would
  26 have been written, which would usually result in OOB later), including
  27 the ending \0 for fmt0()
  28
  29 - warn if truncation happened (instead of ignoring)
  30
  31 Other less common cases can still be handled with strcpy/snprintf() etc.
  32
  33 Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
  34 Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
  35 Message-Id: <20200127092414.169796-2-marcandre.lureau@redhat.com>
  36 Signed-off-by: Oguz Bektas <o.bektas@proxmox.com>
  37 ---
  38  slirp/src/util.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
  39  slirp/src/util.h |  3 +++
  40  2 files changed, 65 insertions(+)
  41
  42 diff --git a/slirp/src/util.c b/slirp/src/util.c
  43 index e596087..e3b6257 100644
  44 --- a/slirp/src/util.c
  45 +++ b/slirp/src/util.c
  46 @@ -364,3 +364,65 @@ void slirp_pstrcpy(char *buf, int buf_size, const char *str)
  47      }
  48      *q = '\0';
  49  }
  50 +
  51 +static int slirp_vsnprintf(char *str, size_t size,
  52 +                           const char *format, va_list args)
  53 +{
  54 +    int rv = vsnprintf(str, size, format, args);
  55 +
  56 +    if (rv < 0) {
  57 +        g_error("vsnprintf() failed: %s", g_strerror(errno));
  58 +    }
  59 +
  60 +    return rv;
  61 +}
  62 +
  63 +/*
  64 + * A snprintf()-like function that:
  65 + * - returns the number of bytes written (excluding optional \0-ending)
  66 + * - dies on error
  67 + * - warn on truncation
  68 + */
  69 +int slirp_fmt(char *str, size_t size, const char *format, ...)
  70 +{
  71 +    va_list args;
  72 +    int rv;
  73 +
  74 +    va_start(args, format);
  75 +    rv = slirp_vsnprintf(str, size, format, args);
  76 +    va_end(args);
  77 +
  78 +    if (rv > size) {
  79 +        g_critical("vsnprintf() truncation");
  80 +    }
  81 +
  82 +    return MIN(rv, size);
  83 +}
  84 +
  85 +/*
  86 + * A snprintf()-like function that:
  87 + * - always \0-end (unless size == 0)
  88 + * - returns the number of bytes actually written, including \0 ending
  89 + * - dies on error
  90 + * - warn on truncation
  91 + */
  92 +int slirp_fmt0(char *str, size_t size, const char *format, ...)
  93 +{
  94 +    va_list args;
  95 +    int rv;
  96 +
  97 +    va_start(args, format);
  98 +    rv = slirp_vsnprintf(str, size, format, args);
  99 +    va_end(args);
 100 +
 101 +    if (rv >= size) {
 102 +        g_critical("vsnprintf() truncation");
 103 +        if (size > 0)
 104 +            str[size - 1] = '\0';
 105 +        rv = size;
 106 +    } else {
 107 +        rv += 1; /* include \0 */
 108 +    }
 109 +
 110 +    return rv;
 111 +}
 112 diff --git a/slirp/src/util.h b/slirp/src/util.h
 113 index 3c6223c..0558dfc 100644
 114 --- a/slirp/src/util.h
 115 +++ b/slirp/src/util.h
 116 @@ -177,4 +177,7 @@ static inline int slirp_socket_set_fast_reuse(int fd)
 117
 118  void slirp_pstrcpy(char *buf, int buf_size, const char *str);
 119
 120 +int slirp_fmt(char *str, size_t size, const char *format, ...);
 121 +int slirp_fmt0(char *str, size_t size, const char *format, ...);
 122 +
 123  #endif
 124 --
 125 2.20.1
 126