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s390/zcrypt: Use scnprintf() for avoiding potential buffer overflow
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Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit.  Fix it by replacing with scnprintf().

Message-Id: <20200311090915.21059-1-tiwai@suse.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Takashi Iwai authored and Vasily Gorbik committed Mar 23, 2020
1 parent 52aeda7 commit eb3e064
Showing 1 changed file with 21 additions and 19 deletions.
40 changes: 21 additions & 19 deletions drivers/s390/crypto/zcrypt_cex4.c
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Original file line number Diff line number Diff line change
Expand Up @@ -128,16 +128,18 @@ static ssize_t cca_mkvps_show(struct device *dev,
n = snprintf(buf, PAGE_SIZE, "AES NEW: - -\n");

if (ci.cur_mk_state >= '1' && ci.cur_mk_state <= '2')
n += snprintf(buf + n, PAGE_SIZE - n, "AES CUR: %s 0x%016llx\n",
cao_state[ci.cur_mk_state - '1'], ci.cur_mkvp);
n += scnprintf(buf + n, PAGE_SIZE - n,
"AES CUR: %s 0x%016llx\n",
cao_state[ci.cur_mk_state - '1'], ci.cur_mkvp);
else
n += snprintf(buf + n, PAGE_SIZE - n, "AES CUR: - -\n");
n += scnprintf(buf + n, PAGE_SIZE - n, "AES CUR: - -\n");

if (ci.old_mk_state >= '1' && ci.old_mk_state <= '2')
n += snprintf(buf + n, PAGE_SIZE - n, "AES OLD: %s 0x%016llx\n",
cao_state[ci.old_mk_state - '1'], ci.old_mkvp);
n += scnprintf(buf + n, PAGE_SIZE - n,
"AES OLD: %s 0x%016llx\n",
cao_state[ci.old_mk_state - '1'], ci.old_mkvp);
else
n += snprintf(buf + n, PAGE_SIZE - n, "AES OLD: - -\n");
n += scnprintf(buf + n, PAGE_SIZE - n, "AES OLD: - -\n");

return n;
}
Expand Down Expand Up @@ -251,11 +253,11 @@ static ssize_t ep11_card_op_modes_show(struct device *dev,
if (ci.op_mode & (1 << ep11_op_modes[i].mode_bit)) {
if (n > 0)
buf[n++] = ' ';
n += snprintf(buf + n, PAGE_SIZE - n,
"%s", ep11_op_modes[i].mode_txt);
n += scnprintf(buf + n, PAGE_SIZE - n,
"%s", ep11_op_modes[i].mode_txt);
}
}
n += snprintf(buf + n, PAGE_SIZE - n, "\n");
n += scnprintf(buf + n, PAGE_SIZE - n, "\n");

return n;
}
Expand Down Expand Up @@ -305,21 +307,21 @@ static ssize_t ep11_mkvps_show(struct device *dev,
cwk_state[di.cur_wk_state - '0']);
bin2hex(buf + n, di.cur_wkvp, sizeof(di.cur_wkvp));
n += 2 * sizeof(di.cur_wkvp);
n += snprintf(buf + n, PAGE_SIZE - n, "\n");
n += scnprintf(buf + n, PAGE_SIZE - n, "\n");
} else
n = snprintf(buf, PAGE_SIZE, "WK CUR: - -\n");

if (di.new_wk_state == '0') {
n += snprintf(buf + n, PAGE_SIZE - n, "WK NEW: %s -\n",
nwk_state[di.new_wk_state - '0']);
n += scnprintf(buf + n, PAGE_SIZE - n, "WK NEW: %s -\n",
nwk_state[di.new_wk_state - '0']);
} else if (di.new_wk_state >= '1' && di.new_wk_state <= '2') {
n += snprintf(buf + n, PAGE_SIZE - n, "WK NEW: %s 0x",
nwk_state[di.new_wk_state - '0']);
n += scnprintf(buf + n, PAGE_SIZE - n, "WK NEW: %s 0x",
nwk_state[di.new_wk_state - '0']);
bin2hex(buf + n, di.new_wkvp, sizeof(di.new_wkvp));
n += 2 * sizeof(di.new_wkvp);
n += snprintf(buf + n, PAGE_SIZE - n, "\n");
n += scnprintf(buf + n, PAGE_SIZE - n, "\n");
} else
n += snprintf(buf + n, PAGE_SIZE - n, "WK NEW: - -\n");
n += scnprintf(buf + n, PAGE_SIZE - n, "WK NEW: - -\n");

return n;
}
Expand All @@ -346,11 +348,11 @@ static ssize_t ep11_queue_op_modes_show(struct device *dev,
if (di.op_mode & (1 << ep11_op_modes[i].mode_bit)) {
if (n > 0)
buf[n++] = ' ';
n += snprintf(buf + n, PAGE_SIZE - n,
"%s", ep11_op_modes[i].mode_txt);
n += scnprintf(buf + n, PAGE_SIZE - n,
"%s", ep11_op_modes[i].mode_txt);
}
}
n += snprintf(buf + n, PAGE_SIZE - n, "\n");
n += scnprintf(buf + n, PAGE_SIZE - n, "\n");

return n;
}
Expand Down

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