Tarantool development patches archive
 help / color / mirror / Atom feed
From: Sergey Nikiforov <void@tarantool.org>
To: tarantool-patches@dev.tarantool.org
Cc: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
Subject: [Tarantool-patches] [PATCH v2 1/2] base64: Fix decoder output buffer overrun (reads)
Date: Tue, 15 Dec 2020 17:22:45 +0300	[thread overview]
Message-ID: <8df71aaa6f1d18ed6892c9bc1826bc694a4c81d2.1608041781.git.void@tarantool.org> (raw)
In-Reply-To: <cover.1608041781.git.void@tarantool.org>

Was caught by base64 test with enabled ASAN.

It also caused data corruption - garbage instead of "extra bits" was
saved into state->result if there was no space in output buffer.

Fixes: #3069
---

Branch: https://github.com/tarantool/tarantool/tree/void234/gh-3069-fix-base64-memory-overrun-v2
Issue: https://github.com/tarantool/tarantool/issues/3069

 third_party/base64.c | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/third_party/base64.c b/third_party/base64.c
index 8ecab23eb..3350a98ff 100644
--- a/third_party/base64.c
+++ b/third_party/base64.c
@@ -247,8 +247,9 @@ base64_decode_block(const char *in_base64, int in_len,
 	char *out_pos = out_bin;
 	char *out_end = out_bin + out_len;
 	int fragment;
+	char curr_byte;
 
-	*out_pos = state->result;
+	curr_byte = state->result;
 
 	switch (state->step)
 	{
@@ -259,49 +260,54 @@ base64_decode_block(const char *in_base64, int in_len,
 				if (in_pos == in_end || out_pos >= out_end)
 				{
 					state->step = step_a;
-					state->result = *out_pos;
+					state->result = curr_byte;
 					return out_pos - out_bin;
 				}
 				fragment = base64_decode_value(*in_pos++);
 			} while (fragment < 0);
-			*out_pos    = (fragment & 0x03f) << 2;
+			curr_byte = (fragment & 0x03f) << 2;
 	case step_b:
 			do {
 				if (in_pos == in_end || out_pos >= out_end)
 				{
 					state->step = step_b;
-					state->result = *out_pos;
+					state->result = curr_byte;
 					return out_pos - out_bin;
 				}
 				fragment = base64_decode_value(*in_pos++);
 			} while (fragment < 0);
-			*out_pos++ |= (fragment & 0x030) >> 4;
+			curr_byte |= (fragment & 0x030) >> 4;
+			*out_pos++ = curr_byte;
+			curr_byte = (fragment & 0x00f) << 4;
 			if (out_pos < out_end)
-				*out_pos = (fragment & 0x00f) << 4;
+				*out_pos = curr_byte;
 	case step_c:
 			do {
 				if (in_pos == in_end || out_pos >= out_end)
 				{
 					state->step = step_c;
-					state->result = *out_pos;
+					state->result = curr_byte;
 					return out_pos - out_bin;
 				}
 				fragment = base64_decode_value(*in_pos++);
 			} while (fragment < 0);
-			*out_pos++ |= (fragment & 0x03c) >> 2;
+			curr_byte |= (fragment & 0x03c) >> 2;
+			*out_pos++ = curr_byte;
+			curr_byte = (fragment & 0x003) << 6;
 			if (out_pos < out_end)
-				*out_pos = (fragment & 0x003) << 6;
+				*out_pos = curr_byte;
 	case step_d:
 			do {
 				if (in_pos == in_end || out_pos >= out_end)
 				{
 					state->step = step_d;
-					state->result = *out_pos;
+					state->result = curr_byte;
 					return out_pos - out_bin;
 				}
 				fragment = base64_decode_value(*in_pos++);
 			} while (fragment < 0);
-			*out_pos++   |= (fragment & 0x03f);
+			curr_byte |= (fragment & 0x03f);
+			*out_pos++ = curr_byte;
 		}
 	}
 	/* control should not reach here */
-- 
2.25.1

  reply	other threads:[~2020-12-15 14:23 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-15 14:22 [Tarantool-patches] [PATCH v2 0/2] base64: Fix decoder, improve its performance Sergey Nikiforov
2020-12-15 14:22 ` Sergey Nikiforov [this message]
2020-12-15 14:22 ` [Tarantool-patches] [PATCH v2 2/2] base64: Improve decoder performance Sergey Nikiforov
2020-12-16 23:22   ` Vladislav Shpilevoy
2020-12-17 12:43     ` Sergey Nikiforov
2020-12-20 16:27       ` Vladislav Shpilevoy
2020-12-22 10:30         ` Sergey Nikiforov
2020-12-22 15:05           ` Vladislav Shpilevoy
2020-12-22 16:08             ` Sergey Nikiforov
2020-12-22 16:39               ` Vladislav Shpilevoy
2020-12-25 10:39                 ` Sergey Nikiforov
2020-12-26 13:25                   ` Vladislav Shpilevoy

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=8df71aaa6f1d18ed6892c9bc1826bc694a4c81d2.1608041781.git.void@tarantool.org \
    --to=void@tarantool.org \
    --cc=tarantool-patches@dev.tarantool.org \
    --cc=v.shpilevoy@tarantool.org \
    --subject='Re: [Tarantool-patches] [PATCH v2 1/2] base64: Fix decoder output buffer overrun (reads)' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox