Several fixups to shmem_parse_param() and tmpfs use of new mount API: mm/shmem.c manages filesystem named "tmpfs": revert "shmem" to "tmpfs" in its mount error messages.
/sys/kernel/mm/transparent_hugepage/shmem_enabled has valid options "deny" and "force", but they are not valid as tmpfs "huge" options. The "size" param is an alternative to "nr_blocks", and needs to be recognized as changing max_blocks. And where there's ambiguity, it's better to mention "size" than "nr_blocks" in messages, since "size" is the variant shown in /proc/mounts. shmem_apply_options() left ctx->mpol as the new mpol, so then it was freed in shmem_free_fc(), and the filesystem went on to use-after-free. shmem_parse_param() issue "tmpfs: Bad value for '%s'" messages just like fs_parse() would, instead of a different wording. Where config disables "mpol" or "huge", say "tmpfs: Unsupported parameter '%s'". Signed-off-by: Hugh Dickins <[email protected]> --- mm/shmem.c | 80 ++++++++++++++++++++++++++------------------------- 1 file changed, 42 insertions(+), 38 deletions(-) --- mmotm/mm/shmem.c 2019-08-17 11:33:16.557900238 -0700 +++ linux/mm/shmem.c 2019-08-19 13:37:29.184001050 -0700 @@ -3432,13 +3432,11 @@ static const struct fs_parameter_enum sh { Opt_huge, "always", SHMEM_HUGE_ALWAYS }, { Opt_huge, "within_size", SHMEM_HUGE_WITHIN_SIZE }, { Opt_huge, "advise", SHMEM_HUGE_ADVISE }, - { Opt_huge, "deny", SHMEM_HUGE_DENY }, - { Opt_huge, "force", SHMEM_HUGE_FORCE }, {} }; const struct fs_parameter_description shmem_fs_parameters = { - .name = "shmem", + .name = "tmpfs", .specs = shmem_param_specs, .enums = shmem_param_enums, }; @@ -3448,9 +3446,9 @@ static void shmem_apply_options(struct s unsigned long inodes_in_use) { struct shmem_fs_context *ctx = fc->fs_private; - struct mempolicy *old = NULL; - if (test_bit(Opt_nr_blocks, &ctx->changes)) + if (test_bit(Opt_nr_blocks, &ctx->changes) || + test_bit(Opt_size, &ctx->changes)) sbinfo->max_blocks = ctx->max_blocks; if (test_bit(Opt_nr_inodes, &ctx->changes)) { sbinfo->max_inodes = ctx->max_inodes; @@ -3459,8 +3457,11 @@ static void shmem_apply_options(struct s if (test_bit(Opt_huge, &ctx->changes)) sbinfo->huge = ctx->huge; if (test_bit(Opt_mpol, &ctx->changes)) { - old = sbinfo->mpol; - sbinfo->mpol = ctx->mpol; + /* + * Update sbinfo->mpol now while stat_lock is held. + * Leave shmem_free_fc() to free the old mpol if any. + */ + swap(sbinfo->mpol, ctx->mpol); } if (fc->purpose != FS_CONTEXT_FOR_RECONFIGURE) { @@ -3471,8 +3472,6 @@ static void shmem_apply_options(struct s if (test_bit(Opt_mode, &ctx->changes)) sbinfo->mode = ctx->mode; } - - mpol_put(old); } static int shmem_parse_param(struct fs_context *fc, struct fs_parameter *param) @@ -3498,7 +3497,7 @@ static int shmem_parse_param(struct fs_c rest++; } if (*rest) - return invalf(fc, "shmem: Invalid size"); + goto bad_value; ctx->max_blocks = DIV_ROUND_UP(size, PAGE_SIZE); break; @@ -3506,55 +3505,59 @@ static int shmem_parse_param(struct fs_c rest = param->string; ctx->max_blocks = memparse(param->string, &rest); if (*rest) - return invalf(fc, "shmem: Invalid nr_blocks"); + goto bad_value; break; + case Opt_nr_inodes: rest = param->string; ctx->max_inodes = memparse(param->string, &rest); if (*rest) - return invalf(fc, "shmem: Invalid nr_inodes"); + goto bad_value; break; + case Opt_mode: ctx->mode = result.uint_32 & 07777; break; + case Opt_uid: ctx->uid = make_kuid(current_user_ns(), result.uint_32); if (!uid_valid(ctx->uid)) - return invalf(fc, "shmem: Invalid uid"); + goto bad_value; break; case Opt_gid: ctx->gid = make_kgid(current_user_ns(), result.uint_32); if (!gid_valid(ctx->gid)) - return invalf(fc, "shmem: Invalid gid"); + goto bad_value; break; case Opt_huge: -#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE - if (!has_transparent_hugepage() && - result.uint_32 != SHMEM_HUGE_NEVER) - return invalf(fc, "shmem: Huge pages disabled"); - ctx->huge = result.uint_32; + if (ctx->huge != SHMEM_HUGE_NEVER && + !(IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) && + has_transparent_hugepage())) + goto unsupported_parameter; break; -#else - return invalf(fc, "shmem: huge= option disabled"); -#endif - - case Opt_mpol: { -#ifdef CONFIG_NUMA - struct mempolicy *mpol; - if (mpol_parse_str(param->string, &mpol)) - return invalf(fc, "shmem: Invalid mpol="); - mpol_put(ctx->mpol); - ctx->mpol = mpol; -#endif - break; - } + + case Opt_mpol: + if (IS_ENABLED(CONFIG_NUMA)) { + struct mempolicy *mpol; + if (mpol_parse_str(param->string, &mpol)) + goto bad_value; + mpol_put(ctx->mpol); + ctx->mpol = mpol; + break; + } + goto unsupported_parameter; } __set_bit(opt, &ctx->changes); return 0; + +unsupported_parameter: + return invalf(fc, "tmpfs: Unsupported parameter '%s'", param->key); +bad_value: + return invalf(fc, "tmpfs: Bad value for '%s'", param->key); } /* @@ -3572,14 +3575,15 @@ static int shmem_reconfigure(struct fs_c unsigned long inodes_in_use; spin_lock(&sbinfo->stat_lock); - if (test_bit(Opt_nr_blocks, &ctx->changes)) { + if (test_bit(Opt_nr_blocks, &ctx->changes) || + test_bit(Opt_size, &ctx->changes)) { if (ctx->max_blocks && !sbinfo->max_blocks) { spin_unlock(&sbinfo->stat_lock); - return invalf(fc, "shmem: Can't retroactively limit nr_blocks"); + return invalf(fc, "tmpfs: Cannot retroactively limit size"); } if (percpu_counter_compare(&sbinfo->used_blocks, ctx->max_blocks) > 0) { spin_unlock(&sbinfo->stat_lock); - return invalf(fc, "shmem: Too few blocks for current use"); + return invalf(fc, "tmpfs: Too small a size for current use"); } } @@ -3587,11 +3591,11 @@ static int shmem_reconfigure(struct fs_c if (test_bit(Opt_nr_inodes, &ctx->changes)) { if (ctx->max_inodes && !sbinfo->max_inodes) { spin_unlock(&sbinfo->stat_lock); - return invalf(fc, "shmem: Can't retroactively limit nr_inodes"); + return invalf(fc, "tmpfs: Cannot retroactively limit inodes"); } if (ctx->max_inodes < inodes_in_use) { spin_unlock(&sbinfo->stat_lock); - return invalf(fc, "shmem: Too few inodes for current use"); + return invalf(fc, "tmpfs: Too few inodes for current use"); } }
