From 0e1edbd99994270023cea5afe593f972eb09a778 Mon Sep 17 00:00:00 2001 From: Nathan Scott Date: Thu, 10 Aug 2006 14:40:41 +1000 Subject: [PATCH] [XFS] Fix xfs_free_extent related NULL pointer dereference. We recently fixed an out-of-space deadlock in XFS, and part of that fix involved the addition of the XFS_ALLOC_FLAG_FREEING flag to some of the space allocator calls to indicate they're freeing space, not allocating it. There was a missed xfs_alloc_fix_freelist condition test that did not correctly test "flags". The same test would also test an uninitialised structure field (args->userdata) and depending on its value either would or would not return early with a critical buffer pointer set to NULL. This fixes that up, adds asserts to several places to catch future botches of this nature, and skips sections of xfs_alloc_fix_freelist that are irrelevent for the space-freeing case. SGI-PV: 955303 SGI-Modid: xfs-linux-melb:xfs-kern:26743a Signed-off-by: Nathan Scott --- fs/xfs/xfs_alloc.c | 103 ++++++++++++++++++++++++--------------------- 1 file changed, 54 insertions(+), 49 deletions(-) diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c index eef6763f3a..d2bbcd882a 100644 --- a/fs/xfs/xfs_alloc.c +++ b/fs/xfs/xfs_alloc.c @@ -1835,40 +1835,47 @@ xfs_alloc_fix_freelist( &agbp))) return error; if (!pag->pagf_init) { + ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK); + ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING)); args->agbp = NULL; return 0; } } else agbp = NULL; - /* If this is a metadata preferred pag and we are user data + /* + * If this is a metadata preferred pag and we are user data * then try somewhere else if we are not being asked to * try harder at this point */ - if (pag->pagf_metadata && args->userdata && flags) { + if (pag->pagf_metadata && args->userdata && + (flags & XFS_ALLOC_FLAG_TRYLOCK)) { + ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING)); args->agbp = NULL; return 0; } - need = XFS_MIN_FREELIST_PAG(pag, mp); - delta = need > pag->pagf_flcount ? need - pag->pagf_flcount : 0; - /* - * If it looks like there isn't a long enough extent, or enough - * total blocks, reject it. - */ - longest = (pag->pagf_longest > delta) ? - (pag->pagf_longest - delta) : - (pag->pagf_flcount > 0 || pag->pagf_longest > 0); - if (args->minlen + args->alignment + args->minalignslop - 1 > longest || - (!(flags & XFS_ALLOC_FLAG_FREEING) && - (int)(pag->pagf_freeblks + pag->pagf_flcount - - need - args->total) < - (int)args->minleft)) { - if (agbp) - xfs_trans_brelse(tp, agbp); - args->agbp = NULL; - return 0; + if (!(flags & XFS_ALLOC_FLAG_FREEING)) { + need = XFS_MIN_FREELIST_PAG(pag, mp); + delta = need > pag->pagf_flcount ? need - pag->pagf_flcount : 0; + /* + * If it looks like there isn't a long enough extent, or enough + * total blocks, reject it. + */ + longest = (pag->pagf_longest > delta) ? + (pag->pagf_longest - delta) : + (pag->pagf_flcount > 0 || pag->pagf_longest > 0); + if ((args->minlen + args->alignment + args->minalignslop - 1) > + longest || + ((int)(pag->pagf_freeblks + pag->pagf_flcount - + need - args->total) < (int)args->minleft)) { + if (agbp) + xfs_trans_brelse(tp, agbp); + args->agbp = NULL; + return 0; + } } + /* * Get the a.g. freespace buffer. * Can fail if we're not blocking on locks, and it's held. @@ -1878,6 +1885,8 @@ xfs_alloc_fix_freelist( &agbp))) return error; if (agbp == NULL) { + ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK); + ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING)); args->agbp = NULL; return 0; } @@ -1887,22 +1896,24 @@ xfs_alloc_fix_freelist( */ agf = XFS_BUF_TO_AGF(agbp); need = XFS_MIN_FREELIST(agf, mp); - delta = need > be32_to_cpu(agf->agf_flcount) ? - (need - be32_to_cpu(agf->agf_flcount)) : 0; /* * If there isn't enough total or single-extent, reject it. */ - longest = be32_to_cpu(agf->agf_longest); - longest = (longest > delta) ? (longest - delta) : - (be32_to_cpu(agf->agf_flcount) > 0 || longest > 0); - if (args->minlen + args->alignment + args->minalignslop - 1 > longest || - (!(flags & XFS_ALLOC_FLAG_FREEING) && - (int)(be32_to_cpu(agf->agf_freeblks) + - be32_to_cpu(agf->agf_flcount) - need - args->total) < - (int)args->minleft)) { - xfs_trans_brelse(tp, agbp); - args->agbp = NULL; - return 0; + if (!(flags & XFS_ALLOC_FLAG_FREEING)) { + delta = need > be32_to_cpu(agf->agf_flcount) ? + (need - be32_to_cpu(agf->agf_flcount)) : 0; + longest = be32_to_cpu(agf->agf_longest); + longest = (longest > delta) ? (longest - delta) : + (be32_to_cpu(agf->agf_flcount) > 0 || longest > 0); + if ((args->minlen + args->alignment + args->minalignslop - 1) > + longest || + ((int)(be32_to_cpu(agf->agf_freeblks) + + be32_to_cpu(agf->agf_flcount) - need - args->total) < + (int)args->minleft)) { + xfs_trans_brelse(tp, agbp); + args->agbp = NULL; + return 0; + } } /* * Make the freelist shorter if it's too long. @@ -1950,12 +1961,11 @@ xfs_alloc_fix_freelist( * on a completely full ag. */ if (targs.agbno == NULLAGBLOCK) { - if (!(flags & XFS_ALLOC_FLAG_FREEING)) { - xfs_trans_brelse(tp, agflbp); - args->agbp = NULL; - return 0; - } - break; + if (flags & XFS_ALLOC_FLAG_FREEING) + break; + xfs_trans_brelse(tp, agflbp); + args->agbp = NULL; + return 0; } /* * Put each allocated block on the list. @@ -2442,31 +2452,26 @@ xfs_free_extent( xfs_fsblock_t bno, /* starting block number of extent */ xfs_extlen_t len) /* length of extent */ { -#ifdef DEBUG - xfs_agf_t *agf; /* a.g. freespace header */ -#endif - xfs_alloc_arg_t args; /* allocation argument structure */ + xfs_alloc_arg_t args; int error; ASSERT(len != 0); + memset(&args, 0, sizeof(xfs_alloc_arg_t)); args.tp = tp; args.mp = tp->t_mountp; args.agno = XFS_FSB_TO_AGNO(args.mp, bno); ASSERT(args.agno < args.mp->m_sb.sb_agcount); args.agbno = XFS_FSB_TO_AGBNO(args.mp, bno); - args.alignment = 1; - args.minlen = args.minleft = args.minalignslop = 0; down_read(&args.mp->m_peraglock); args.pag = &args.mp->m_perag[args.agno]; if ((error = xfs_alloc_fix_freelist(&args, XFS_ALLOC_FLAG_FREEING))) goto error0; #ifdef DEBUG ASSERT(args.agbp != NULL); - agf = XFS_BUF_TO_AGF(args.agbp); - ASSERT(args.agbno + len <= be32_to_cpu(agf->agf_length)); + ASSERT((args.agbno + len) <= + be32_to_cpu(XFS_BUF_TO_AGF(args.agbp)->agf_length)); #endif - error = xfs_free_ag_extent(tp, args.agbp, args.agno, args.agbno, - len, 0); + error = xfs_free_ag_extent(tp, args.agbp, args.agno, args.agbno, len, 0); error0: up_read(&args.mp->m_peraglock); return error; -- 2.39.5