89 lines
4.3 KiB
Diff
89 lines
4.3 KiB
Diff
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From cf7a8182c2642c50f1cf90dddea9ce96a8bad2e8 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?J=C3=B6rn=20Heusipp?= <osmanx@problemloesungsmaschine.de>
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Date: Wed, 14 Jun 2017 12:25:40 +0200
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Subject: [PATCH] src/common.c: Fix heap buffer overflows when writing strings
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in binheader
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Fixes the following problems:
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1. Case 's' only enlarges the buffer by 16 bytes instead of size bytes.
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2. psf_binheader_writef() enlarges the header buffer (if needed) prior to the
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big switch statement by an amount (16 bytes) which is enough for all cases
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where only a single value gets added. Cases 's', 'S', 'p' however
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additionally write an arbitrary length block of data and again enlarge the
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buffer to the required amount. However, the required space calculation does
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not take into account the size of the length field which gets output before
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the data.
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3. Buffer size requirement calculation in case 'S' does not account for the
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padding byte ("size += (size & 1) ;" happens after the calculation which
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uses "size").
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4. Case 'S' can overrun the header buffer by 1 byte when no padding is
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involved
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("memcpy (&(psf->header.ptr [psf->header.indx]), strptr, size + 1) ;" while
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the buffer is only guaranteed to have "size" space available).
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5. "psf->header.ptr [psf->header.indx] = 0 ;" in case 'S' always writes 1 byte
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beyond the space which is guaranteed to be allocated in the header buffer.
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6. Case 's' can overrun the provided source string by 1 byte if padding is
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involved ("memcpy (&(psf->header.ptr [psf->header.indx]), strptr, size) ;"
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where "size" is "strlen (strptr) + 1" (which includes the 0 terminator,
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plus optionally another 1 which is padding and not guaranteed to be
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readable via the source string pointer).
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Closes: https://github.com/erikd/libsndfile/issues/292
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---
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src/common.c | 15 +++++++--------
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1 file changed, 7 insertions(+), 8 deletions(-)
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diff --git a/src/common.c b/src/common.c
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index 1a6204ca..6b2a2ee9 100644
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--- a/src/common.c
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+++ b/src/common.c
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@@ -681,16 +681,16 @@ psf_binheader_writef (SF_PRIVATE *psf, const char *format, ...)
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/* Write a C string (guaranteed to have a zero terminator). */
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strptr = va_arg (argptr, char *) ;
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size = strlen (strptr) + 1 ;
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- size += (size & 1) ;
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- if (psf->header.indx + (sf_count_t) size >= psf->header.len && psf_bump_header_allocation (psf, 16))
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+ if (psf->header.indx + 4 + (sf_count_t) size + (sf_count_t) (size & 1) > psf->header.len && psf_bump_header_allocation (psf, 4 + size + (size & 1)))
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return count ;
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if (psf->rwf_endian == SF_ENDIAN_BIG)
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- header_put_be_int (psf, size) ;
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+ header_put_be_int (psf, size + (size & 1)) ;
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else
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- header_put_le_int (psf, size) ;
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+ header_put_le_int (psf, size + (size & 1)) ;
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memcpy (&(psf->header.ptr [psf->header.indx]), strptr, size) ;
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+ size += (size & 1) ;
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psf->header.indx += size ;
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psf->header.ptr [psf->header.indx - 1] = 0 ;
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count += 4 + size ;
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@@ -703,16 +703,15 @@ psf_binheader_writef (SF_PRIVATE *psf, const char *format, ...)
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*/
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strptr = va_arg (argptr, char *) ;
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size = strlen (strptr) ;
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- if (psf->header.indx + (sf_count_t) size > psf->header.len && psf_bump_header_allocation (psf, size))
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+ if (psf->header.indx + 4 + (sf_count_t) size + (sf_count_t) (size & 1) > psf->header.len && psf_bump_header_allocation (psf, 4 + size + (size & 1)))
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return count ;
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if (psf->rwf_endian == SF_ENDIAN_BIG)
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header_put_be_int (psf, size) ;
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else
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header_put_le_int (psf, size) ;
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- memcpy (&(psf->header.ptr [psf->header.indx]), strptr, size + 1) ;
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+ memcpy (&(psf->header.ptr [psf->header.indx]), strptr, size + (size & 1)) ;
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size += (size & 1) ;
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psf->header.indx += size ;
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- psf->header.ptr [psf->header.indx] = 0 ;
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count += 4 + size ;
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break ;
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@@ -724,7 +723,7 @@ psf_binheader_writef (SF_PRIVATE *psf, const char *format, ...)
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size = (size & 1) ? size : size + 1 ;
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size = (size > 254) ? 254 : size ;
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- if (psf->header.indx + (sf_count_t) size > psf->header.len && psf_bump_header_allocation (psf, size))
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+ if (psf->header.indx + 1 + (sf_count_t) size > psf->header.len && psf_bump_header_allocation (psf, 1 + size))
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return count ;
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header_put_byte (psf, size) ;
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