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[libpng16] Reject oversized iCCP profile length

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The code now validates the ICC profile length against the user chunk limit
before the buffer is allocated, as opposed to doing it while the buffer is read.

This removes the potential to consume virtual address space with a carefully
crafted ICC profile; only an issue on 32-bit systems where a valid profile can
be up to 2^32-4 bytes in length.  libpng never writes beyond the application
supplied limit, but previously it did allocate a buffer of the size specified in
the profile header.  The exploitability of this is almost zero; the address
space is released as soon as the PNG read completes.

Also clean up PNG_DEBUG compile of pngtest.c.

Signed-off-by: John Bowler <jbowler@acm.org>
This commit is contained in:
John Bowler
2016-08-10 15:35:09 -07:00
parent cdc0e74ee6
commit 92a7c79db2
5 changed files with 85 additions and 38 deletions
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2
pngpriv.h
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@@ -1494,9 +1494,11 @@ PNG_INTERNAL_FUNCTION(int,png_colorspace_set_ICC,(png_const_structrp png_ptr,
/* The 'name' is used for information only */
/* Routines for checking parts of an ICC profile. */
#ifdef PNG_READ_iCCP_SUPPORTED
PNG_INTERNAL_FUNCTION(int,png_icc_check_length,(png_const_structrp png_ptr,
png_colorspacerp colorspace, png_const_charp name,
png_uint_32 profile_length), PNG_EMPTY);
#endif /* READ_iCCP */
PNG_INTERNAL_FUNCTION(int,png_icc_check_header,(png_const_structrp png_ptr,
png_colorspacerp colorspace, png_const_charp name,
png_uint_32 profile_length,