Crash in ComputeGradient (coutln.cpp)

[Aaargh20318]

I'm currently seeing a SIGBUS crash in ComputeGradient on an Android app I'm working on, I can reliably reproduce the crash on a specific phone (Samsung Galaxy S4 Mini, Snapdragon 400), on another device (OnePlus One, Snapdragon 801)

Backtrace (app name removed):

D/CrashAnrDetector( 656): backtrace:
D/CrashAnrDetector( 656): #00 pc 000a746c /data/app-lib/APPNAME/libtess.so
D/CrashAnrDetector( 656): #1 pc 000a8935 /data/app-lib/APPNAME/libtess.so (C_OUTLINE::ComputeEdgeOffsets(int, Pix_)+160)
D/CrashAnrDetector( 656): #2 pc 000b81b1 /data/app-lib/APPNAME/libtess.so
D/CrashAnrDetector( 656): #3 pc 000a3a1d /data/app-lib/APPNAME/libtess.so (BLOBNBOX::ComputeEdgeOffsets(Pix_, Pix_, BLOBNBOX_LIST_)+212)
D/CrashAnrDetector( 656): #4 pc 000a42b7 /data/app-lib/APPNAME/libtess.so (TO_BLOCK::ComputeEdgeOffsets(Pix_, Pix_)+14)
D/CrashAnrDetector( 656): #5 pc 0011f099 /data/app-lib/APPNAME/libtess.so (tesseract::Textord::TextordPage(tesseract::PageSegMode, FCOORD const&, int, int, Pix_, Pix_, Pix_, bool, BLOBNBOX_LIST_, BLOCK_LIST_, TO_BLOCK_LIST_)+72)

I added some debug output to ComputeGradient and it turns out it crashes when y = -2. , after adding a few more lines of debug logging in ComputeEdgeOffsets I see that start.y() is 2 larger than 'height'. If it crashes, it always does so on line 2 of ComputeGradient. SIGBUS would imply an unaligned memory access but as far as I can tell that function only deals with single byte access which shouldn't cause an issue. The -2 y coordinate also seems suspect but I don't know enough about Tesseract and Pix to know if that might be a problem or not.

[zdenop]

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