lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 7 Feb 2011 13:29:03 +0100 From: Steffen Klassert <steffen.klassert@...unet.com> To: Dave Hansen <dave@...ux.vnet.ibm.com> Cc: Andrew Morton <akpm@...ux-foundation.org>, Eric Paris <eparis@...hat.com>, linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org Subject: [PATCH v2] flex_array: Change behaviour on zero size allocations flex_array_alloc allocates the basic struct flex_array regardless whether total_nr_elements or element_size is zero. Then flex_array_prealloc fails with -ENOSPC if total_nr_elements is zero or it hits a division by zero if element_size is zero. This patch changes the behaviour on zero size allocations to the same as kmalloc, so zero size allocations are leagal now. We also change flex_array_prealloc to take the number of elements for which space should be allocated instead of the last (inclusive) element. Users and documentation are updated accordingly. This fixes a regression on selinux policy loading. Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com> --- Documentation/flexible-arrays.txt | 4 +- include/linux/flex_array.h | 2 +- lib/flex_array.c | 48 ++++++++++++++++++++++++++++-------- security/selinux/ss/policydb.c | 6 ++-- 4 files changed, 43 insertions(+), 17 deletions(-) diff --git a/Documentation/flexible-arrays.txt b/Documentation/flexible-arrays.txt index cb8a3a0..df904ae 100644 --- a/Documentation/flexible-arrays.txt +++ b/Documentation/flexible-arrays.txt @@ -66,10 +66,10 @@ trick is to ensure that any needed memory allocations are done before entering atomic context, using: int flex_array_prealloc(struct flex_array *array, unsigned int start, - unsigned int end, gfp_t flags); + unsigned int nr_elements, gfp_t flags); This function will ensure that memory for the elements indexed in the range -defined by start and end has been allocated. Thereafter, a +defined by start and nr_elements has been allocated. Thereafter, a flex_array_put() call on an element in that range is guaranteed not to block. diff --git a/include/linux/flex_array.h b/include/linux/flex_array.h index 70e4efa..ebeb2f3 100644 --- a/include/linux/flex_array.h +++ b/include/linux/flex_array.h @@ -61,7 +61,7 @@ struct flex_array { struct flex_array *flex_array_alloc(int element_size, unsigned int total, gfp_t flags); int flex_array_prealloc(struct flex_array *fa, unsigned int start, - unsigned int end, gfp_t flags); + unsigned int nr_elements, gfp_t flags); void flex_array_free(struct flex_array *fa); void flex_array_free_parts(struct flex_array *fa); int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src, diff --git a/lib/flex_array.c b/lib/flex_array.c index c0ea40b..dcd91d5 100644 --- a/lib/flex_array.c +++ b/lib/flex_array.c @@ -88,8 +88,11 @@ struct flex_array *flex_array_alloc(int element_size, unsigned int total, gfp_t flags) { struct flex_array *ret; - int max_size = FLEX_ARRAY_NR_BASE_PTRS * - FLEX_ARRAY_ELEMENTS_PER_PART(element_size); + int max_size = 0; + + if (element_size) + max_size = FLEX_ARRAY_NR_BASE_PTRS * + FLEX_ARRAY_ELEMENTS_PER_PART(element_size); /* max_size will end up 0 if element_size > PAGE_SIZE */ if (total > max_size) @@ -183,15 +186,18 @@ __fa_get_part(struct flex_array *fa, int part_nr, gfp_t flags) int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src, gfp_t flags) { - int part_nr = fa_element_to_part_nr(fa, element_nr); + int part_nr; struct flex_array_part *part; void *dst; if (element_nr >= fa->total_nr_elements) return -ENOSPC; + if (!fa->element_size) + return 0; if (elements_fit_in_base(fa)) part = (struct flex_array_part *)&fa->parts[0]; else { + part_nr = fa_element_to_part_nr(fa, element_nr); part = __fa_get_part(fa, part_nr, flags); if (!part) return -ENOMEM; @@ -211,15 +217,18 @@ EXPORT_SYMBOL(flex_array_put); */ int flex_array_clear(struct flex_array *fa, unsigned int element_nr) { - int part_nr = fa_element_to_part_nr(fa, element_nr); + int part_nr; struct flex_array_part *part; void *dst; if (element_nr >= fa->total_nr_elements) return -ENOSPC; + if (!fa->element_size) + return 0; if (elements_fit_in_base(fa)) part = (struct flex_array_part *)&fa->parts[0]; else { + part_nr = fa_element_to_part_nr(fa, element_nr); part = fa->parts[part_nr]; if (!part) return -EINVAL; @@ -232,10 +241,10 @@ EXPORT_SYMBOL(flex_array_clear); /** * flex_array_prealloc - guarantee that array space exists - * @fa: the flex array for which to preallocate parts - * @start: index of first array element for which space is allocated - * @end: index of last (inclusive) element for which space is allocated - * @flags: page allocation flags + * @fa: the flex array for which to preallocate parts + * @start: index of first array element for which space is allocated + * @nr_elements: number of elements for which space is allocated + * @flags: page allocation flags * * This will guarantee that no future calls to flex_array_put() * will allocate memory. It can be used if you are expecting to @@ -245,15 +254,27 @@ EXPORT_SYMBOL(flex_array_clear); * Locking must be provided by the caller. */ int flex_array_prealloc(struct flex_array *fa, unsigned int start, - unsigned int end, gfp_t flags) + unsigned int nr_elements, gfp_t flags) { int start_part; int end_part; int part_nr; + unsigned int end; struct flex_array_part *part; - if (start >= fa->total_nr_elements || end >= fa->total_nr_elements) + if (!fa->total_nr_elements && !start) + return 0; + if (start >= fa->total_nr_elements) + return -ENOSPC; + if (!nr_elements) + return 0; + + end = start + nr_elements - 1; + + if (end >= fa->total_nr_elements) return -ENOSPC; + if (!fa->element_size) + return 0; if (elements_fit_in_base(fa)) return 0; start_part = fa_element_to_part_nr(fa, start); @@ -281,14 +302,17 @@ EXPORT_SYMBOL(flex_array_prealloc); */ void *flex_array_get(struct flex_array *fa, unsigned int element_nr) { - int part_nr = fa_element_to_part_nr(fa, element_nr); + int part_nr; struct flex_array_part *part; + if (!fa->element_size) + return NULL; if (element_nr >= fa->total_nr_elements) return NULL; if (elements_fit_in_base(fa)) part = (struct flex_array_part *)&fa->parts[0]; else { + part_nr = fa_element_to_part_nr(fa, element_nr); part = fa->parts[part_nr]; if (!part) return NULL; @@ -343,6 +367,8 @@ int flex_array_shrink(struct flex_array *fa) int part_nr; int ret = 0; + if (!fa->total_nr_elements || !fa->element_size) + return 0; if (elements_fit_in_base(fa)) return ret; for (part_nr = 0; part_nr < FLEX_ARRAY_NR_BASE_PTRS; part_nr++) { diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c index 5736356..f96f09c 100644 --- a/security/selinux/ss/policydb.c +++ b/security/selinux/ss/policydb.c @@ -497,7 +497,7 @@ static int policydb_index(struct policydb *p) goto out; rc = flex_array_prealloc(p->type_val_to_struct_array, 0, - p->p_types.nprim - 1, GFP_KERNEL | __GFP_ZERO); + p->p_types.nprim, GFP_KERNEL | __GFP_ZERO); if (rc) goto out; @@ -514,7 +514,7 @@ static int policydb_index(struct policydb *p) goto out; rc = flex_array_prealloc(p->sym_val_to_name[i], - 0, p->symtab[i].nprim - 1, + 0, p->symtab[i].nprim, GFP_KERNEL | __GFP_ZERO); if (rc) goto out; @@ -2286,7 +2286,7 @@ int policydb_read(struct policydb *p, void *fp) goto bad; /* preallocate so we don't have to worry about the put ever failing */ - rc = flex_array_prealloc(p->type_attr_map_array, 0, p->p_types.nprim - 1, + rc = flex_array_prealloc(p->type_attr_map_array, 0, p->p_types.nprim, GFP_KERNEL | __GFP_ZERO); if (rc) goto bad; -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists