From f7f824e54b842c1e33a8e2e7304cd72def3c622e Mon Sep 17 00:00:00 2001 From: Lasse Collin Date: Sun, 14 Jun 2026 19:05:17 +0300 Subject: [PATCH] lib/xz: use size_t instead of uint32_t in a few places Reduce the number of uint32_t <-> size_t conversions a little. Eliminating such conversions entirely would require changing almost all uint32_t to size_t, which would look confusing and increase the sizes of the structs even more. Going the other way, converting everything to uint32_t, isn't possible because the input and output buffers use size_t in struct xz_buf. Now both arguments to min() have the same type. This is required to for compatibility with PowerPC boot code[1] whose min() is strict like include/linux/minmax.h was before the commit d03eba99f5bf ("minmax: allow min()/max()/clamp() if the arguments have the same signedness."). Swap the order of the "state" and "len" in struct lzma_dec to avoid padding in the middle of the struct when size_t is 64 bits. The reordering doesn't change the size of the struct; the padding just appears at the end instead. dict_flush() used to truncate size_t to uint32_t when returning. This wasn't a bug; the value is always small enough. Link: https://lore.kernel.org/20260614160521.924710-1-lasse.collin@tukaani.org Signed-off-by: Lasse Collin Reported-by: Nathan Chancellor Closes: https://lore.kernel.org/lkml/20260610232323.GA1071374@ax162/ [1] Reviewed-by: Thorsten Blum Cc: David Laight Signed-off-by: Andrew Morton --- lib/xz/xz_dec_lzma2.c | 40 ++++++++++++++++++++-------------------- lib/xz/xz_lzma2.h | 2 +- 2 files changed, 21 insertions(+), 21 deletions(-) diff --git a/lib/xz/xz_dec_lzma2.c b/lib/xz/xz_dec_lzma2.c index 9d80342b9c6b..68ae9c33b6a8 100644 --- a/lib/xz/xz_dec_lzma2.c +++ b/lib/xz/xz_dec_lzma2.c @@ -135,14 +135,16 @@ struct lzma_dec { uint32_t rep2; uint32_t rep3; - /* Types of the most recently seen LZMA symbols */ - enum lzma_state state; - /* * Length of a match. This is updated so that dict_repeat can - * be called again to finish repeating the whole match. + * be called again to finish repeating the whole match. This is + * size_t because a pointer to this is passed to dict_repeat, + * and there it's nicer to have size_t instead of uint32_t. */ - uint32_t len; + size_t len; + + /* Types of the most recently seen LZMA symbols */ + enum lzma_state state; /* * LZMA properties or related bit masks (number of literal @@ -228,13 +230,13 @@ struct lzma2_dec { enum lzma2_seq next_sequence; /* Uncompressed size of LZMA chunk (2 MiB at maximum) */ - uint32_t uncompressed; + size_t uncompressed; /* * Compressed size of LZMA chunk or compressed/uncompressed * size of uncompressed chunk (64 KiB at maximum) */ - uint32_t compressed; + size_t compressed; /* * True if dictionary reset is needed. This is false before @@ -273,7 +275,7 @@ struct xz_dec_lzma2 { * decoder calls. See lzma2_lzma() for details. */ struct { - uint32_t size; + size_t size; uint8_t buf[3 * LZMA_IN_REQUIRED]; } temp; }; @@ -320,7 +322,7 @@ static inline bool dict_has_space(const struct dictionary *dict) * still empty. This special case is needed for single-call decoding to * avoid writing a '\0' to the end of the destination buffer. */ -static inline uint32_t dict_get(const struct dictionary *dict, uint32_t dist) +static inline uint32_t dict_get(const struct dictionary *dict, size_t dist) { size_t offset = dict->pos - dist - 1; @@ -346,10 +348,10 @@ static inline void dict_put(struct dictionary *dict, uint8_t byte) * invalid, false is returned. On success, true is returned and *len is * updated to indicate how many bytes were left to be repeated. */ -static bool dict_repeat(struct dictionary *dict, uint32_t *len, uint32_t dist) +static bool dict_repeat(struct dictionary *dict, size_t *len, size_t dist) { size_t back; - uint32_t left; + size_t left; if (dist >= dict->full || dist >= dict->size) return false; @@ -375,7 +377,7 @@ static bool dict_repeat(struct dictionary *dict, uint32_t *len, uint32_t dist) /* Copy uncompressed data as is from input to dictionary and output buffers. */ static void dict_uncompressed(struct dictionary *dict, struct xz_buf *b, - uint32_t *left) + size_t *left) { size_t copy_size; @@ -433,7 +435,7 @@ static void dict_uncompressed(struct dictionary *dict, struct xz_buf *b, * enough space in b->out. This is guaranteed because caller uses dict_limit() * before decoding data into the dictionary. */ -static uint32_t dict_flush(struct dictionary *dict, struct xz_buf *b) +static size_t dict_flush(struct dictionary *dict, struct xz_buf *b) { size_t copy_size = dict->pos - dict->start; @@ -878,7 +880,7 @@ static bool lzma_props(struct xz_dec_lzma2 *s, uint8_t props) static bool lzma2_lzma(struct xz_dec_lzma2 *s, struct xz_buf *b) { size_t in_avail; - uint32_t tmp; + size_t tmp; in_avail = b->in_size - b->in_pos; if (s->temp.size > 0 || s->lzma2.compressed == 0) { @@ -1046,25 +1048,23 @@ enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s, struct xz_buf *b) case SEQ_UNCOMPRESSED_1: s->lzma2.uncompressed - += (uint32_t)b->in[b->in_pos++] << 8; + += (size_t)b->in[b->in_pos++] << 8; s->lzma2.sequence = SEQ_UNCOMPRESSED_2; break; case SEQ_UNCOMPRESSED_2: s->lzma2.uncompressed - += (uint32_t)b->in[b->in_pos++] + 1; + += (size_t)b->in[b->in_pos++] + 1; s->lzma2.sequence = SEQ_COMPRESSED_0; break; case SEQ_COMPRESSED_0: - s->lzma2.compressed - = (uint32_t)b->in[b->in_pos++] << 8; + s->lzma2.compressed = (size_t)b->in[b->in_pos++] << 8; s->lzma2.sequence = SEQ_COMPRESSED_1; break; case SEQ_COMPRESSED_1: - s->lzma2.compressed - += (uint32_t)b->in[b->in_pos++] + 1; + s->lzma2.compressed += (size_t)b->in[b->in_pos++] + 1; s->lzma2.sequence = s->lzma2.next_sequence; break; diff --git a/lib/xz/xz_lzma2.h b/lib/xz/xz_lzma2.h index d2632b7dfb9c..a612ce4fd450 100644 --- a/lib/xz/xz_lzma2.h +++ b/lib/xz/xz_lzma2.h @@ -143,7 +143,7 @@ static inline bool lzma_state_is_literal(enum lzma_state state) * Get the index of the appropriate probability array for decoding * the distance slot. */ -static inline uint32_t lzma_get_dist_state(uint32_t len) +static inline size_t lzma_get_dist_state(size_t len) { return len < DIST_STATES + MATCH_LEN_MIN ? len - MATCH_LEN_MIN : DIST_STATES - 1;