Mercurial > hg > nginx-quic
view src/core/ngx_parse.c @ 7629:f47f7d3d1bfa
Mp4: fixed possible chunk offset overflow.
In "co64" atom chunk start offset is a 64-bit unsigned integer. When trimming
the "mdat" atom, chunk offsets are casted to off_t values which are typically
64-bit signed integers. A specially crafted mp4 file with huge chunk offsets
may lead to off_t overflow and result in negative trim boundaries.
The consequences of the overflow are:
- Incorrect Content-Length header value in the response.
- Negative left boundary of the response file buffer holding the trimmed "mdat".
This leads to pread()/sendfile() errors followed by closing the client
connection.
On rare systems where off_t is a 32-bit integer, this scenario is also feasible
with the "stco" atom.
The fix is to add checks which make sure data chunks referenced by each track
are within the mp4 file boundaries. Additionally a few more checks are added to
ensure mp4 file consistency and log errors.
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Wed, 26 Feb 2020 15:10:46 +0300 |
parents | 87cf6ddb41c2 |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> ssize_t ngx_parse_size(ngx_str_t *line) { u_char unit; size_t len; ssize_t size, scale, max; len = line->len; if (len == 0) { return NGX_ERROR; } unit = line->data[len - 1]; switch (unit) { case 'K': case 'k': len--; max = NGX_MAX_SIZE_T_VALUE / 1024; scale = 1024; break; case 'M': case 'm': len--; max = NGX_MAX_SIZE_T_VALUE / (1024 * 1024); scale = 1024 * 1024; break; default: max = NGX_MAX_SIZE_T_VALUE; scale = 1; } size = ngx_atosz(line->data, len); if (size == NGX_ERROR || size > max) { return NGX_ERROR; } size *= scale; return size; } off_t ngx_parse_offset(ngx_str_t *line) { u_char unit; off_t offset, scale, max; size_t len; len = line->len; if (len == 0) { return NGX_ERROR; } unit = line->data[len - 1]; switch (unit) { case 'K': case 'k': len--; max = NGX_MAX_OFF_T_VALUE / 1024; scale = 1024; break; case 'M': case 'm': len--; max = NGX_MAX_OFF_T_VALUE / (1024 * 1024); scale = 1024 * 1024; break; case 'G': case 'g': len--; max = NGX_MAX_OFF_T_VALUE / (1024 * 1024 * 1024); scale = 1024 * 1024 * 1024; break; default: max = NGX_MAX_OFF_T_VALUE; scale = 1; } offset = ngx_atoof(line->data, len); if (offset == NGX_ERROR || offset > max) { return NGX_ERROR; } offset *= scale; return offset; } ngx_int_t ngx_parse_time(ngx_str_t *line, ngx_uint_t is_sec) { u_char *p, *last; ngx_int_t value, total, scale; ngx_int_t max, cutoff, cutlim; ngx_uint_t valid; enum { st_start = 0, st_year, st_month, st_week, st_day, st_hour, st_min, st_sec, st_msec, st_last } step; valid = 0; value = 0; total = 0; cutoff = NGX_MAX_INT_T_VALUE / 10; cutlim = NGX_MAX_INT_T_VALUE % 10; step = is_sec ? st_start : st_month; p = line->data; last = p + line->len; while (p < last) { if (*p >= '0' && *p <= '9') { if (value >= cutoff && (value > cutoff || *p - '0' > cutlim)) { return NGX_ERROR; } value = value * 10 + (*p++ - '0'); valid = 1; continue; } switch (*p++) { case 'y': if (step > st_start) { return NGX_ERROR; } step = st_year; max = NGX_MAX_INT_T_VALUE / (60 * 60 * 24 * 365); scale = 60 * 60 * 24 * 365; break; case 'M': if (step >= st_month) { return NGX_ERROR; } step = st_month; max = NGX_MAX_INT_T_VALUE / (60 * 60 * 24 * 30); scale = 60 * 60 * 24 * 30; break; case 'w': if (step >= st_week) { return NGX_ERROR; } step = st_week; max = NGX_MAX_INT_T_VALUE / (60 * 60 * 24 * 7); scale = 60 * 60 * 24 * 7; break; case 'd': if (step >= st_day) { return NGX_ERROR; } step = st_day; max = NGX_MAX_INT_T_VALUE / (60 * 60 * 24); scale = 60 * 60 * 24; break; case 'h': if (step >= st_hour) { return NGX_ERROR; } step = st_hour; max = NGX_MAX_INT_T_VALUE / (60 * 60); scale = 60 * 60; break; case 'm': if (p < last && *p == 's') { if (is_sec || step >= st_msec) { return NGX_ERROR; } p++; step = st_msec; max = NGX_MAX_INT_T_VALUE; scale = 1; break; } if (step >= st_min) { return NGX_ERROR; } step = st_min; max = NGX_MAX_INT_T_VALUE / 60; scale = 60; break; case 's': if (step >= st_sec) { return NGX_ERROR; } step = st_sec; max = NGX_MAX_INT_T_VALUE; scale = 1; break; case ' ': if (step >= st_sec) { return NGX_ERROR; } step = st_last; max = NGX_MAX_INT_T_VALUE; scale = 1; break; default: return NGX_ERROR; } if (step != st_msec && !is_sec) { scale *= 1000; max /= 1000; } if (value > max) { return NGX_ERROR; } value *= scale; if (total > NGX_MAX_INT_T_VALUE - value) { return NGX_ERROR; } total += value; value = 0; while (p < last && *p == ' ') { p++; } } if (!valid) { return NGX_ERROR; } if (!is_sec) { if (value > NGX_MAX_INT_T_VALUE / 1000) { return NGX_ERROR; } value *= 1000; } if (total > NGX_MAX_INT_T_VALUE - value) { return NGX_ERROR; } return total + value; }