| Message ID | 20240730172301.231867-4-thorsten.blum@toblux.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] ext4: Annotate struct ext4_xattr_inode_array with __counted_by() | expand |
On Tue, Jul 30, 2024 at 07:23:04PM +0200, Thorsten Blum wrote: > Add the __counted_by compiler attribute to the flexible array member > inodes to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and > CONFIG_FORTIFY_SOURCE. > > Remove the now obsolete comment on the count field. > > Refactor ext4_expand_inode_array() by assigning count before copying any > data using memcpy(). Copy only the inodes array instead of the whole > struct because count has been set explicitly. > > Use struct_size() and struct_size_t() instead of offsetof(). > > Change the data type of the local variable count to unsigned int to > match the struct's count data type. > > Compile-tested only. > > Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com> > --- > Changes in v2: > - Adjust ext4_expand_inode_array() as suggested by Gustavo A. R. Silva > - Use struct_size() and struct_size_t() instead of offsetof() > - Link to v1: https://lore.kernel.org/linux-kernel/20240729110454.346918-3-thorsten.blum@toblux.com/ > --- > fs/ext4/xattr.c | 20 +++++++++----------- > fs/ext4/xattr.h | 4 ++-- > 2 files changed, 11 insertions(+), 13 deletions(-) > > diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c > index 46ce2f21fef9..b27543587103 100644 > --- a/fs/ext4/xattr.c > +++ b/fs/ext4/xattr.c > @@ -2879,11 +2879,10 @@ ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array, > if (*ea_inode_array == NULL) { > /* > * Start with 15 inodes, so it fits into a power-of-two size. > - * If *ea_inode_array is NULL, this is essentially offsetof() > */ > (*ea_inode_array) = > - kmalloc(offsetof(struct ext4_xattr_inode_array, > - inodes[EIA_MASK]), > + kmalloc(struct_size_t(struct ext4_xattr_inode_array, This can be struct_size(*ea_inode_array, ...) too, like you have below. > + inodes, EIA_MASK), > GFP_NOFS); > if (*ea_inode_array == NULL) > return -ENOMEM; > @@ -2891,17 +2890,16 @@ ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array, > } else if (((*ea_inode_array)->count & EIA_MASK) == EIA_MASK) { > /* expand the array once all 15 + n * 16 slots are full */ > struct ext4_xattr_inode_array *new_array = NULL; > - int count = (*ea_inode_array)->count; > + unsigned int count = (*ea_inode_array)->count; > > - /* if new_array is NULL, this is essentially offsetof() */ > - new_array = kmalloc( > - offsetof(struct ext4_xattr_inode_array, > - inodes[count + EIA_INCR]), > - GFP_NOFS); > + new_array = kmalloc(struct_size(*ea_inode_array, inodes, > + count + EIA_INCR), > + GFP_NOFS); > if (new_array == NULL) > return -ENOMEM; > - memcpy(new_array, *ea_inode_array, > - offsetof(struct ext4_xattr_inode_array, inodes[count])); > + new_array->count = count; > + memcpy(new_array->inodes, (*ea_inode_array)->inodes, > + count * sizeof(struct inode *)); > kfree(*ea_inode_array); > *ea_inode_array = new_array; > } > diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h > index bd97c4aa8177..e14fb19dc912 100644 > --- a/fs/ext4/xattr.h > +++ b/fs/ext4/xattr.h > @@ -130,8 +130,8 @@ struct ext4_xattr_ibody_find { > }; > > struct ext4_xattr_inode_array { > - unsigned int count; /* # of used items in the array */ > - struct inode *inodes[]; > + unsigned int count; > + struct inode *inodes[] __counted_by(count); > }; > > extern const struct xattr_handler ext4_xattr_user_handler; Thanks for the reworking!
On 30/07/24 11:23, Thorsten Blum wrote: > Add the __counted_by compiler attribute to the flexible array member > inodes to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and > CONFIG_FORTIFY_SOURCE. > > Remove the now obsolete comment on the count field. > > Refactor ext4_expand_inode_array() by assigning count before copying any > data using memcpy(). Copy only the inodes array instead of the whole > struct because count has been set explicitly. > > Use struct_size() and struct_size_t() instead of offsetof(). > > Change the data type of the local variable count to unsigned int to > match the struct's count data type. > > Compile-tested only. > > Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com> > --- > Changes in v2: > - Adjust ext4_expand_inode_array() as suggested by Gustavo A. R. Silva > - Use struct_size() and struct_size_t() instead of offsetof() > - Link to v1: https://lore.kernel.org/linux-kernel/20240729110454.346918-3-thorsten.blum@toblux.com/ > --- > fs/ext4/xattr.c | 20 +++++++++----------- > fs/ext4/xattr.h | 4 ++-- > 2 files changed, 11 insertions(+), 13 deletions(-) > > diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c > index 46ce2f21fef9..b27543587103 100644 > --- a/fs/ext4/xattr.c > +++ b/fs/ext4/xattr.c > @@ -2879,11 +2879,10 @@ ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array, > if (*ea_inode_array == NULL) { > /* > * Start with 15 inodes, so it fits into a power-of-two size. > - * If *ea_inode_array is NULL, this is essentially offsetof() > */ > (*ea_inode_array) = > - kmalloc(offsetof(struct ext4_xattr_inode_array, > - inodes[EIA_MASK]), > + kmalloc(struct_size_t(struct ext4_xattr_inode_array, > + inodes, EIA_MASK), As Kees previously commented, you can use struct_size() here. > GFP_NOFS); > if (*ea_inode_array == NULL) > return -ENOMEM; > @@ -2891,17 +2890,16 @@ ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array, > } else if (((*ea_inode_array)->count & EIA_MASK) == EIA_MASK) { > /* expand the array once all 15 + n * 16 slots are full */ > struct ext4_xattr_inode_array *new_array = NULL; > - int count = (*ea_inode_array)->count; > + unsigned int count = (*ea_inode_array)->count; It seems `count` is not actually needed anymore. If you remove it and directly use `(*ea_inode_array)->count` in the following call to `kmalloc()`, you could use `struct_size()` in the call to `memcpy()` below, and copy the whole thing in one line. See below. > > - /* if new_array is NULL, this is essentially offsetof() */ > - new_array = kmalloc( > - offsetof(struct ext4_xattr_inode_array, > - inodes[count + EIA_INCR]), > - GFP_NOFS); > + new_array = kmalloc(struct_size(*ea_inode_array, inodes, > + count + EIA_INCR), > + GFP_NOFS); > if (new_array == NULL) > return -ENOMEM; > - memcpy(new_array, *ea_inode_array, > - offsetof(struct ext4_xattr_inode_array, inodes[count])); > + new_array->count = count; > + memcpy(new_array->inodes, (*ea_inode_array)->inodes, > + count * sizeof(struct inode *)); memcpy(new_array, *ea_inode_array, struct_size(new_array, inodes, (*ea_inode_array)->count)); > kfree(*ea_inode_array); > *ea_inode_array = new_array; > } Also, you are missing one more like just below this one, where `(*ea_inode_array)->count` is currently being used to directly index `inodes`: (*ea_inode_array)->inodes[(*ea_inode_array)->count++] = inode; Thanks -- Gustavo > diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h > index bd97c4aa8177..e14fb19dc912 100644 > --- a/fs/ext4/xattr.h > +++ b/fs/ext4/xattr.h > @@ -130,8 +130,8 @@ struct ext4_xattr_ibody_find { > }; > > struct ext4_xattr_inode_array { > - unsigned int count; /* # of used items in the array */ > - struct inode *inodes[]; > + unsigned int count; > + struct inode *inodes[] __counted_by(count); > }; > > extern const struct xattr_handler ext4_xattr_user_handler;
On 30. Jul 2024, at 20:12, Gustavo A. R. Silva <gustavo@embeddedor.com> wrote: > On 30/07/24 11:23, Thorsten Blum wrote: >> Add the __counted_by compiler attribute to the flexible array member >> inodes to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and >> CONFIG_FORTIFY_SOURCE. >> Remove the now obsolete comment on the count field. >> Refactor ext4_expand_inode_array() by assigning count before copying any >> data using memcpy(). Copy only the inodes array instead of the whole >> struct because count has been set explicitly. >> Use struct_size() and struct_size_t() instead of offsetof(). >> Change the data type of the local variable count to unsigned int to >> match the struct's count data type. >> Compile-tested only. >> Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com> >> --- >> Changes in v2: >> - Adjust ext4_expand_inode_array() as suggested by Gustavo A. R. Silva >> - Use struct_size() and struct_size_t() instead of offsetof() >> - Link to v1: https://lore.kernel.org/linux-kernel/20240729110454.346918-3-thorsten.blum@toblux.com/ >> --- >> fs/ext4/xattr.c | 20 +++++++++----------- >> fs/ext4/xattr.h | 4 ++-- >> 2 files changed, 11 insertions(+), 13 deletions(-) >> diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c >> index 46ce2f21fef9..b27543587103 100644 >> --- a/fs/ext4/xattr.c >> +++ b/fs/ext4/xattr.c >> @@ -2879,11 +2879,10 @@ ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array, >> if (*ea_inode_array == NULL) { >> /* >> * Start with 15 inodes, so it fits into a power-of-two size. >> - * If *ea_inode_array is NULL, this is essentially offsetof() >> */ >> (*ea_inode_array) = >> - kmalloc(offsetof(struct ext4_xattr_inode_array, >> - inodes[EIA_MASK]), >> + kmalloc(struct_size_t(struct ext4_xattr_inode_array, >> + inodes, EIA_MASK), > > As Kees previously commented, you can use struct_size() here. > >> GFP_NOFS); >> if (*ea_inode_array == NULL) >> return -ENOMEM; >> @@ -2891,17 +2890,16 @@ ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array, >> } else if (((*ea_inode_array)->count & EIA_MASK) == EIA_MASK) { >> /* expand the array once all 15 + n * 16 slots are full */ >> struct ext4_xattr_inode_array *new_array = NULL; >> - int count = (*ea_inode_array)->count; >> + unsigned int count = (*ea_inode_array)->count; > > It seems `count` is not actually needed anymore. > > If you remove it and directly use `(*ea_inode_array)->count` in the following > call to `kmalloc()`, you could use `struct_size()` in the call to `memcpy()` > below, and copy the whole thing in one line. See below. > >> - /* if new_array is NULL, this is essentially offsetof() */ >> - new_array = kmalloc( >> - offsetof(struct ext4_xattr_inode_array, >> - inodes[count + EIA_INCR]), >> - GFP_NOFS); >> + new_array = kmalloc(struct_size(*ea_inode_array, inodes, >> + count + EIA_INCR), >> + GFP_NOFS); >> if (new_array == NULL) >> return -ENOMEM; >> - memcpy(new_array, *ea_inode_array, >> - offsetof(struct ext4_xattr_inode_array, inodes[count])); >> + new_array->count = count; >> + memcpy(new_array->inodes, (*ea_inode_array)->inodes, >> + count * sizeof(struct inode *)); > > memcpy(new_array, *ea_inode_array, struct_size(new_array, inodes, (*ea_inode_array)->count)); > >> kfree(*ea_inode_array); >> *ea_inode_array = new_array; >> } > > Also, you are missing one more like just below this one, where `(*ea_inode_array)->count` > is currently being used to directly index `inodes`: > > (*ea_inode_array)->inodes[(*ea_inode_array)->count++] = inode; Thanks, I missed this one. Thorsten
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 46ce2f21fef9..b27543587103 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -2879,11 +2879,10 @@ ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array, if (*ea_inode_array == NULL) { /* * Start with 15 inodes, so it fits into a power-of-two size. - * If *ea_inode_array is NULL, this is essentially offsetof() */ (*ea_inode_array) = - kmalloc(offsetof(struct ext4_xattr_inode_array, - inodes[EIA_MASK]), + kmalloc(struct_size_t(struct ext4_xattr_inode_array, + inodes, EIA_MASK), GFP_NOFS); if (*ea_inode_array == NULL) return -ENOMEM; @@ -2891,17 +2890,16 @@ ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array, } else if (((*ea_inode_array)->count & EIA_MASK) == EIA_MASK) { /* expand the array once all 15 + n * 16 slots are full */ struct ext4_xattr_inode_array *new_array = NULL; - int count = (*ea_inode_array)->count; + unsigned int count = (*ea_inode_array)->count; - /* if new_array is NULL, this is essentially offsetof() */ - new_array = kmalloc( - offsetof(struct ext4_xattr_inode_array, - inodes[count + EIA_INCR]), - GFP_NOFS); + new_array = kmalloc(struct_size(*ea_inode_array, inodes, + count + EIA_INCR), + GFP_NOFS); if (new_array == NULL) return -ENOMEM; - memcpy(new_array, *ea_inode_array, - offsetof(struct ext4_xattr_inode_array, inodes[count])); + new_array->count = count; + memcpy(new_array->inodes, (*ea_inode_array)->inodes, + count * sizeof(struct inode *)); kfree(*ea_inode_array); *ea_inode_array = new_array; } diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h index bd97c4aa8177..e14fb19dc912 100644 --- a/fs/ext4/xattr.h +++ b/fs/ext4/xattr.h @@ -130,8 +130,8 @@ struct ext4_xattr_ibody_find { }; struct ext4_xattr_inode_array { - unsigned int count; /* # of used items in the array */ - struct inode *inodes[]; + unsigned int count; + struct inode *inodes[] __counted_by(count); }; extern const struct xattr_handler ext4_xattr_user_handler;
Add the __counted_by compiler attribute to the flexible array member inodes to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE. Remove the now obsolete comment on the count field. Refactor ext4_expand_inode_array() by assigning count before copying any data using memcpy(). Copy only the inodes array instead of the whole struct because count has been set explicitly. Use struct_size() and struct_size_t() instead of offsetof(). Change the data type of the local variable count to unsigned int to match the struct's count data type. Compile-tested only. Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com> --- Changes in v2: - Adjust ext4_expand_inode_array() as suggested by Gustavo A. R. Silva - Use struct_size() and struct_size_t() instead of offsetof() - Link to v1: https://lore.kernel.org/linux-kernel/20240729110454.346918-3-thorsten.blum@toblux.com/ --- fs/ext4/xattr.c | 20 +++++++++----------- fs/ext4/xattr.h | 4 ++-- 2 files changed, 11 insertions(+), 13 deletions(-)