fix(tiff): check for invalid bit depth for palette images#5091
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lgritz wants to merge 1 commit intoAcademySoftwareFoundation:mainfrom
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fix(tiff): check for invalid bit depth for palette images#5091lgritz wants to merge 1 commit intoAcademySoftwareFoundation:mainfrom
lgritz wants to merge 1 commit intoAcademySoftwareFoundation:mainfrom
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Reading the TIFF 6.0 spec, on p. 23, it sure looks like palette images can only be 4 or 8 bits per sample. But the libtiff set of test images indeed has 2, 4, 8, and yes, 16 bps palette images among the examples. So I think we should support up to 16, since we might encounter it in the wild, but no higher. We didn't previously check for this, though, and that could lead to accepting invalid TIFF files, and then potentially have problems with `(1 << m_bitspersample)` which appears several times. That of course is safe if m_bitspersample can't be > 16. Also check and proper error for a file that has a bitspersample that is not one of the valid choices (1, 2, 4, 6, 8, 10, 12, 14, 16, 24, 32, 64), and proper errors for if the sampleformat was an unknown value or was not a valid value for the number of bits per sample. Note that this changes the reference output of some tests because the new checks can alter the first error discovered in a corrupt file. Signed-off-by: Larry Gritz <lg@larrygritz.com>
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Reading the TIFF 6.0 spec, on p. 23, it sure looks like palette images can only be 4 or 8 bits per sample. But the libtiff set of test images indeed has 2, 4, 8, and yes, 16 bps palette images among the examples. So I think we should support up to 16, since we might encounter it in the wild, but no higher.
We didn't previously check for this, though, and that could lead to accepting invalid TIFF files, and then potentially have problems with
(1 << m_bitspersample)which appears several times. That of course is safe if m_bitspersample can't be > 16.Also check and proper error for a file that has a bitspersample that is not one of the valid choices (1, 2, 4, 6, 8, 10, 12, 14, 16, 24, 32, 64), and proper errors for if the sampleformat was an unknown value or was not a valid value for the number of bits per sample.
Note that this changes the reference output of some tests because the new checks can alter the first error discovered in a corrupt file.