[PATCH] x86: deflate stack usage in lib/inflate.c

inflate_fixed and huft_build together use around 2.7k of stack.  When
using 4k stacks, I saw stack overflows from interrupts arriving while
unpacking the root initrd:

do_IRQ: stack overflow: 384
 [<c0106b64>] show_trace_log_lvl+0x1a/0x30
 [<c01075e6>] show_trace+0x12/0x14
 [<c010763f>] dump_stack+0x16/0x18
 [<c0107ca4>] do_IRQ+0x6d/0xd9
 [<c010202b>] xen_evtchn_do_upcall+0x6e/0xa2
 [<c0106781>] xen_hypervisor_callback+0x25/0x2c
 [<c010116c>] xen_restore_fl+0x27/0x29
 [<c0330f63>] _spin_unlock_irqrestore+0x4a/0x50
 [<c0117aab>] change_page_attr+0x577/0x584
 [<c0117b45>] kernel_map_pages+0x8d/0xb4
 [<c016a314>] cache_alloc_refill+0x53f/0x632
 [<c016a6c2>] __kmalloc+0xc1/0x10d
 [<c0463d34>] malloc+0x10/0x12
 [<c04641c1>] huft_build+0x2a7/0x5fa
 [<c04645a5>] inflate_fixed+0x91/0x136
 [<c04657e2>] unpack_to_rootfs+0x5f2/0x8c1
 [<c0465acf>] populate_rootfs+0x1e/0xe4

(This was under Xen, but there's no reason it couldn't happen on bare
  hardware.)

This patch mallocs the local variables, thereby reducing the stack
usage to sane levels.

Also, up the heap size for the kernel decompressor to deal with the
extra allocation.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Tim Yamin <plasmaroo@gentoo.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ian Molton <spyro@f2s.com>

diff --git a/arch/alpha/boot/misc.c b/arch/alpha/boot/misc.c
index 1d65adf5691e6fab0e66535afeb09d9b6ae62c24..c00646b25f6e961862900c8e13bd69cb31a89823 100644 (file)
--- a/arch/alpha/boot/misc.c
+++ b/arch/alpha/boot/misc.c
@@ -98,7 +98,7 @@ extern int end;
 static ulg free_mem_ptr;
 static ulg free_mem_ptr_end;
 
-#define HEAP_SIZE 0x2000
+#define HEAP_SIZE 0x3000
 
 #include "../../../lib/inflate.c"
 

diff --git a/arch/arm/boot/compressed/misc.c b/arch/arm/boot/compressed/misc.c
index 283891c736c4a9a92ab9f336f93b23ba83dfe956..9b444022cb9bc76933f1fdba6dffb294723fd7ac 100644 (file)
--- a/arch/arm/boot/compressed/misc.c
+++ b/arch/arm/boot/compressed/misc.c
@@ -239,7 +239,7 @@ extern int end;
 static ulg free_mem_ptr;
 static ulg free_mem_ptr_end;
 
-#define HEAP_SIZE 0x2000
+#define HEAP_SIZE 0x3000
 
 #include "../../../../lib/inflate.c"
 

diff --git a/arch/arm26/boot/compressed/misc.c b/arch/arm26/boot/compressed/misc.c
index f17f50e5516fef6797d3ae4ee3b457b7416e6125..0714d19c577636f655889726efbeabb887cfca24 100644 (file)
--- a/arch/arm26/boot/compressed/misc.c
+++ b/arch/arm26/boot/compressed/misc.c
@@ -182,7 +182,7 @@ extern int end;
 static ulg free_mem_ptr;
 static ulg free_mem_ptr_end;
 
-#define HEAP_SIZE 0x2000
+#define HEAP_SIZE 0x3000
 
 #include "../../../../lib/inflate.c"
 

diff --git a/arch/i386/boot/compressed/misc.c b/arch/i386/boot/compressed/misc.c
index 1ce7017fd62706ccb02e1d5b34c683bd6537677c..b28505c544c9ca60306c5029326fb82b16ef4b95 100644 (file)
--- a/arch/i386/boot/compressed/misc.c
+++ b/arch/i386/boot/compressed/misc.c
@@ -189,7 +189,7 @@ static void putstr(const char *);
 static unsigned long free_mem_ptr;
 static unsigned long free_mem_end_ptr;
 
-#define HEAP_SIZE             0x3000
+#define HEAP_SIZE             0x4000
 
 static char *vidmem = (char *)0xb8000;
 static int vidport;

diff --git a/arch/x86_64/boot/compressed/misc.c b/arch/x86_64/boot/compressed/misc.c
index fed1167159c342a3bda42fd560eda1b7537711fb..f932b0e89096afaf0eefdcf723a27d1957c4a3d5 100644 (file)
--- a/arch/x86_64/boot/compressed/misc.c
+++ b/arch/x86_64/boot/compressed/misc.c
@@ -189,7 +189,7 @@ static void putstr(const char *);
 static long free_mem_ptr;
 static long free_mem_end_ptr;
 
-#define HEAP_SIZE             0x6000
+#define HEAP_SIZE             0x7000
 
 static char *vidmem = (char *)0xb8000;
 static int vidport;

diff --git a/lib/inflate.c b/lib/inflate.c
index 6db6e98d1637b58764d3356a52ecff7216dfe3ed..88a22f4a49dfb84f49c01e63f4682d2198419a9b 100644 (file)
--- a/lib/inflate.c
+++ b/lib/inflate.c
@@ -292,7 +292,6 @@ STATIC int INIT huft_build(
    oversubscribed set of lengths), and three if not enough memory. */
 {
   unsigned a;                   /* counter for codes of length k */
-  unsigned c[BMAX+1];           /* bit length count table */
   unsigned f;                   /* i repeats in table every f entries */
   int g;                        /* maximum code length */
   int h;                        /* table level */
@@ -303,18 +302,33 @@ STATIC int INIT huft_build(
   register unsigned *p;         /* pointer into c[], b[], or v[] */
   register struct huft *q;      /* points to current table */
   struct huft r;                /* table entry for structure assignment */
-  struct huft *u[BMAX];         /* table stack */
-  unsigned v[N_MAX];            /* values in order of bit length */
   register int w;               /* bits before this table == (l * h) */
-  unsigned x[BMAX+1];           /* bit offsets, then code stack */
   unsigned *xp;                 /* pointer into x */
   int y;                        /* number of dummy codes added */
   unsigned z;                   /* number of entries in current table */
+  struct {
+    unsigned c[BMAX+1];           /* bit length count table */
+    struct huft *u[BMAX];         /* table stack */
+    unsigned v[N_MAX];            /* values in order of bit length */
+    unsigned x[BMAX+1];           /* bit offsets, then code stack */
+  } *stk;
+  unsigned *c, *v, *x;
+  struct huft **u;
+  int ret;
 
 DEBG("huft1 ");
 
+  stk = malloc(sizeof(*stk));
+  if (stk == NULL)
+    return 3;                  /* out of memory */
+
+  c = stk->c;
+  v = stk->v;
+  x = stk->x;
+  u = stk->u;
+
   /* Generate counts for each bit length */
-  memzero(c, sizeof(c));
+  memzero(stk->c, sizeof(stk->c));
   p = b;  i = n;
   do {
     Tracecv(*p, (stderr, (n-i >= ' ' && n-i <= '~' ? "%c %d\n" : "0x%x %d\n"), 
@@ -326,7 +340,8 @@ DEBG("huft1 ");
   {
     *t = (struct huft *)NULL;
     *m = 0;
-    return 2;
+    ret = 2;
+    goto out;
   }
 
 DEBG("huft2 ");
@@ -351,10 +366,14 @@ DEBG("huft3 ");
 
   /* Adjust last length count to fill out codes, if needed */
   for (y = 1 << j; j < i; j++, y <<= 1)
-    if ((y -= c[j]) < 0)
-      return 2;                 /* bad input: more codes than bits */
-  if ((y -= c[i]) < 0)
-    return 2;
+    if ((y -= c[j]) < 0) {
+      ret = 2;                 /* bad input: more codes than bits */
+      goto out;
+    }
+  if ((y -= c[i]) < 0) {
+    ret = 2;
+    goto out;
+  }
   c[i] += y;
 
 DEBG("huft4 ");
@@ -428,7 +447,8 @@ DEBG1("3 ");
         {
           if (h)
             huft_free(u[0]);
-          return 3;             /* not enough memory */
+          ret = 3;             /* not enough memory */
+         goto out;
         }
 DEBG1("4 ");
         hufts += z + 1;         /* track memory usage */
@@ -492,7 +512,11 @@ DEBG("h6f ");
 DEBG("huft7 ");
 
   /* Return true (1) if we were given an incomplete table */
-  return y != 0 && g != 1;
+  ret = y != 0 && g != 1;
+
+  out:
+  free(stk);
+  return ret;
 }
 
 
@@ -705,10 +729,14 @@ STATIC int noinline INIT inflate_fixed(void)
   struct huft *td;      /* distance code table */
   int bl;               /* lookup bits for tl */
   int bd;               /* lookup bits for td */
-  unsigned l[288];      /* length list for huft_build */
+  unsigned *l;          /* length list for huft_build */
 
 DEBG("<fix");
 
+  l = malloc(sizeof(*l) * 288);
+  if (l == NULL)
+    return 3;                  /* out of memory */
+
   /* set up literal table */
   for (i = 0; i < 144; i++)
     l[i] = 8;
@@ -719,9 +747,10 @@ DEBG("<fix");
   for (; i < 288; i++)          /* make a complete, but wrong code set */
     l[i] = 8;
   bl = 7;
-  if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0)
+  if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0) {
+    free(l);
     return i;
-
+  }
 
   /* set up distance table */
   for (i = 0; i < 30; i++)      /* make an incomplete code set */
@@ -730,6 +759,7 @@ DEBG("<fix");
   if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1)
   {
     huft_free(tl);
+    free(l);
 
     DEBG(">");
     return i;
@@ -737,11 +767,13 @@ DEBG("<fix");
 
 
   /* decompress until an end-of-block code */
-  if (inflate_codes(tl, td, bl, bd))
+  if (inflate_codes(tl, td, bl, bd)) {
+    free(l);
     return 1;
-
+  }
 
   /* free the decoding tables, return */
+  free(l);
   huft_free(tl);
   huft_free(td);
   return 0;