Yifan reported a "segmentation fault (core dumped)" error days ago with a large dataset (enwik9 x 5). Let's fix it.
Reported-by: Yifan Zhao <zhaoyi...@sjtu.edu.cn> Fixes: 861037f4fc15 ("erofs-utils: add a built-in DEFLATE compressor") Signed-off-by: Gao Xiang <hsiang...@linux.alibaba.com> --- include/erofs/defs.h | 3 +++ lib/kite_deflate.c | 12 ++++++++++++ 2 files changed, 15 insertions(+) diff --git a/include/erofs/defs.h b/include/erofs/defs.h index e7384a1..4ea9a55 100644 --- a/include/erofs/defs.h +++ b/include/erofs/defs.h @@ -343,6 +343,9 @@ unsigned long __roundup_pow_of_two(unsigned long n) #define ST_MTIM_NSEC(stbuf) 0 #endif +#define likely(x) __builtin_expect(!!(x), 1) +#define unlikely(x) __builtin_expect(!!(x), 0) + #ifdef __cplusplus } #endif diff --git a/lib/kite_deflate.c b/lib/kite_deflate.c index 8667954..cb81626 100644 --- a/lib/kite_deflate.c +++ b/lib/kite_deflate.c @@ -859,6 +859,18 @@ static void kite_mf_reset(struct kite_matchfinder *mf, */ mf->base += mf->offset + kHistorySize32 + 1; + /* + * Unlike other LZ encoders like liblzma [1], we simply reset the hash + * chain instead of normalization. This avoids extra complexity, as we + * don't consider extreme large input buffers in one go. + * + * [1] https://github.com/tukaani-project/xz/blob/v5.4.0/src/liblzma/lz/lz_encoder_mf.c#L94 + */ + if (unlikely(mf->base > ((typeof(mf->base))-1) >> 1)) { + mf->base = kHistorySize32 + 1; + memset(mf->hash, 0, 0x10000 * sizeof(mf->hash[0])); + memset(mf->chain, 0, sizeof(mf->chain[0]) * mf->wsiz); + } mf->offset = 0; mf->cyclic_pos = 0; -- 2.39.3